Dependency Injection changed the way we write software. Spring overtook EJB’s in thoughtful enterprises, and Guice and PicoContainer are an important part of many well-written applications today.

Automated testing, especially Unit Testing, is also a crucial part of building reliable software that you can feel confident about supporting and changing over its lifetime. Any decent software shop should be writing some tests, the best ones are test-driven and have good code coverage.

Noop is a new language that will run on the Java Virtual Machine, and in source form will look similar to Java. The goal is to build dependency injection and testability into the language from the beginning, rather than rely on third-party libraries as other languages do.

Immutability and minimal variable scope are encouraged by making final/const behavior the default and providing easy access to a functional style. Testability is encouraged by providing Dependency Injection at the language level and a compact constructor injection syntax.

Their Google Code site also has these suggestions for the use of their Noop source files:

1. Java translator: produces Java source. Allows you to use Noop without converting your codebase, but not all runtime features of the language are provided.

2. Interpreter: reads and evaluates the Noop code through an interpreter. Slower, but will have a command-line interface

3. Compiled: to Java bytecode.

Noop is part of the Apache License 2.0 code Licencse. Their getting started page is very informatiove and tells you how to get Noop installed and configured easily. Noop has an extensive features list. I can not see this replacing Java, but I do see it being the main development source for the android in the future.

• Behavior
• Button
• ButtonBase
• CheckBox
• Control
• Hyperlink
• Keystroke
• Label
• Labeled
• ListView
• ProgressBar
• ProgressIndicator
• RadioButton
• ScrollBar
• Skin
• Slider
• TextBox
• TextInputControl
• ToggleButton
• ToggleGroup

To me these are a significant because this will make creating new UI controls a great deal easier then they have been in the past.

JavaFX is a platform for creating and delivering Rich Internet Applications (RIAs) — web applications that use rich media types such as video, audio, graphics, and rich text — that can run in a wide variety of devices, anywhere from handsets-to-laptops-to desktops. In many cases, you can compile and run the same JavaFX application code in a mobile environment, a desktop environment, or in a browser.

• Basic Structure of PL/SQL
• Variables and Types
• Simple PL/SQL Programs
• Control Flow in PL/SQL
• Cursors
• Procedures
• Discovering Errors
• Printing Variables

    DECLARE

    /* Declarative section: variables, types, and local subprograms. */

    BEGIN

    /* Executable section: procedural and SQL statements go here. */

    /* This is the only section of the block that is required. */

    EXCEPTION

    /* Exception handling section: error handling statements go here. */

    END;

Only the executable section is required. The other sections are optional. The only SQL statements allowed in a PL/SQL program are SELECT, INSERT, UPDATE, DELETE and several other data manipulation statements plus some transaction control. However, the SELECT statement has a special form in which a single tuple is placed in variables; more on this later. Data definition statements like CREATE, DROP, or ALTER are not allowed. The executable section also contains constructs such as assignments, branches, loops, procedure calls, and triggers, which are all described below (except triggers). PL/SQL is not case sensitive. C style comments (/* … */) may be used.

To execute a PL/SQL program, we must follow the program text itself by

• A line with a single dot (”.“), and then
• A line with run;

As with Oracle SQL programs, we can invoke a PL/SQL program either by typing it in sqlplus or by putting the code in a file and invoking the file in the various ways we learned in Getting Started With Oracle.

• One of the types used by SQL for database columns
• A generic type used in PL/SQL such as NUMBER
• Declared to be the same as the type of some database column

The most commonly used generic type is NUMBER. Variables of type NUMBER can hold either an integer or a real number. The most commonly used character string type is VARCHAR(n), where n is the maximum length of the string in bytes. This length is required, and there is no default. For example, we might declare:

DECLARE

    price  NUMBER;

    myBeer VARCHAR(20);

Note that PL/SQL allows BOOLEAN variables, even though Oracle does not support BOOLEAN as a type for database columns.

Types in PL/SQL can be tricky. In many cases, a PL/SQL variable will be used to manipulate data stored in a existing relation. In this case, it is essential that the variable have the same type as the relation column. If there is any type mismatch, variable assignments and comparisons may not work the way you expect. To be safe, instead of hard coding the type of a variable, you should use the %TYPE operator. For example:

DECLARE

    myBeer Beers.name%TYPE;

gives PL/SQL variable myBeer whatever type was declared for the name column in relation Beers.

A variable may also have a type that is a record with several fields. The simplest way to declare such a variable is to use %ROWTYPE on a relation name. The result is a record type in which the fields have the same names and types as the attributes of the relation. For instance:

DECLARE

    beerTuple Beers%ROWTYPE;

makes variable beerTuple be a record with fields name and manufacture, assuming that the relation has the schema Beers(name, manufacture)

.

The initial value of any variable, regardless of its type, is NULL. We can assign values to variables, using the “:=” operator. The assignment can occur either immediately after the type of the variable is declared, or anywhere in the executable portion of the program. An example:

DECLARE

    a NUMBER := 3;

BEGIN

    a := a + 1;

END;

.

run;

This program has no effect when run, because there are no changes to the database.

Notice we said “tuple” rather than “tuples”, since the SELECT statement in PL/SQL only works if the result of the query contains a single tuple. The situation is essentially the same as that of the “single-row select” discussed in Section 7.1.5 of the text, in connection with embedded SQL. If the query returns more than one tuple, you need to use a cursor, as described in the next section. Here is an example:

CREATE TABLE T1(

    e INTEGER,

    f INTEGER

);

DELETE FROM T1;

INSERT INTO T1 VALUES(1, 3);

INSERT INTO T1 VALUES(2, 4);

/* Above is plain SQL; below is the PL/SQL program. */

DECLARE

    a NUMBER;

    b NUMBER;

BEGIN

    SELECT e,f INTO a,b FROM T1 WHERE e>1;

    INSERT INTO T1 VALUES(b,a);

END;

.

run;

Fortuitously, there is only one tuple of T1 that has first component greater than 1, namely (2,4). The INSERT statement thus inserts (4,2) into T1

.

An IF statement looks like:

IF <condition> THEN <statement_list> ELSE <statement_list> END IF;

The ELSE part is optional. If you want a multiway branch, use:

IF <condition_1> THEN ...

ELSIF <condition_2> THEN ...

... ...

ELSIF <condition_n> THEN ...

ELSE ...

END IF;

The following is an example, slightly modified from the previous one, where now we only do the insertion if the second component is 1. If not, we first add 10 to each component and then insert:

DECLARE

    a NUMBER;

    b NUMBER;

BEGIN

    SELECT e,f INTO a,b FROM T1 WHERE e>1;

    IF b=1 THEN

        INSERT INTO T1 VALUES(b,a);

    ELSE

        INSERT INTO T1 VALUES(b+10,a+10);

    END IF;

END;

.

run;

Loops are created with the following:

LOOP

    <loop_body> /* A list of statements. */

END LOOP;

At least one of the statements in <loop_body> should be an EXIT statement of the form

EXIT WHEN <condition>;

The loop breaks if <condition> is true. For example, here is a way to insert each of the pairs (1, 1) through (100, 100) into T1 of the above two examples:

DECLARE

    i NUMBER := 1;

BEGIN

    LOOP

        INSERT INTO T1 VALUES(i,i);

        i := i+1;

        EXIT WHEN i>100;

    END LOOP;

END;

.

run;

Some other useful loop-forming statements are:

• EXIT by itself is an unconditional loop break. Use it inside a conditional if you like.
• A WHILE loop can be formed with

      WHILE <condition> LOOP
  
          <loop_body>
  
      END LOOP;

• A simple FOR loop can be formed with:

      FOR <var> IN <start>..<finish> LOOP
  
          <loop_body>
  
      END LOOP;

  Here, <var> can be any variable; it is local to the for-loop and need not be declared. Also, <start> and <finish> are constants.

The example below illustrates a cursor loop. It uses our example relation T1(e,f) whose tuples are pairs of integers. The program will delete every tuple whose first component is less than the second, and insert the reverse tuple into T1.

 1) DECLARE

        /* Output variables to hold the result of the query: */

 2)     a T1.e%TYPE;

 3)     b T1.f%TYPE;

        /* Cursor declaration: */

 4)     CURSOR T1Cursor IS

 5)         SELECT e, f

 6)         FROM T1

 7)         WHERE e < f

 8)         FOR UPDATE;

 9) BEGIN

10)     OPEN T1Cursor;

11)     LOOP

            /* Retrieve each row of the result of the above query

               into PL/SQL variables: */

12)         FETCH T1Cursor INTO a, b;

            /* If there are no more rows to fetch, exit the loop: */

13)         EXIT WHEN T1Cursor%NOTFOUND;

            /* Delete the current tuple: */

14)         DELETE FROM T1 WHERE CURRENT OF T1Cursor;

            /* Insert the reverse tuple: */

15)         INSERT INTO T1 VALUES(b, a);

16)     END LOOP;

        /* Free cursor used by the query. */

17)     CLOSE T1Cursor;

18) END;

19) .

20) run;

Here are explanations for the various lines of this program:

• Line (1) introduces the declaration section.
• Lines (2) and (3) declare variables a and b to have types equal to the types of attributes e and f of the relation T1. Although we know these types are INTEGER, we wisely make sure that whatever types they may have are copied to the PL/SQL variables (compare with the previous example, where we were less careful and declared the corresponding variables to be of type NUMBER).
• Lines (4) through (8) define the cursor T1Cursor. It ranges over a relation defined by the SELECT-FROM-WHERE query. That query selects those tuples of T1 whose first component is less than the second component. Line (8) declares the cursor FOR UPDATE since we will modify T1 using this cursor later on Line (14). In general, FOR UPDATE is unnecessary if the cursor will not be used for modification.
• Line (9) begins the executable section of the program.
• Line (10) opens the cursor, an essential step.
• Lines (11) through (16) are a PL/SQL loop. Notice that such a loop is bracketed by LOOP and END LOOP. Within the loop we find:
  • On Line (12), a fetch through the cursor into the local variables. In general, the FETCH statement must provide variables for each component of the tuple retrieved. Since the query of Lines (5) through (7) produces pairs, we have correctly provided two variables, and we know they are of the correct type.
  • On Line (13), a test for the loop-breaking condition. Its meaning should be clear: %NOTFOUND after the name of a cursor is true exactly when a fetch through that cursor has failed to find any more tuples.
  • On Line (14), a SQL DELETE statement that deletes the current tuple using the special WHERE condition CURRENT OF T1Cursor.
  • On Line (15), a SQL INSERT statement that inserts the reverse tuple into T1.
• Line (17) closes the cursor.
• Line (18) ends the PL/SQL program.
• Lines (19) and (20) cause the program to execute.

CREATE TABLE T2 (

    a INTEGER,

    b CHAR(10)

);

CREATE PROCEDURE addtuple1(i IN NUMBER) AS

BEGIN

    INSERT INTO T2 VALUES(i, 'xxx');

END addtuple1;

.

run;

A procedure is introduced by the keywords CREATE PROCEDURE followed by the procedure name and its parameters. An option is to follow CREATE by OR REPLACE. The advantage of doing so is that should you have already made the definition, you will not get an error. On the other hand, should the previous definition be a different procedure of the same name, you will not be warned, and the old procedure will be lost.

There can be any number of parameters, each followed by a mode and a type. The possible modes are IN (read-only), OUT (write-only), and INOUT (read and write). Note: Unlike the type specifier in a PL/SQL variable declaration, the type specifier in a parameter declaration must be unconstrained. For example, CHAR(10) and VARCHAR(20) are illegal; CHAR or VARCHAR should be used instead. The actual length of a parameter depends on the corresponding argument that is passed in when the procedure is invoked.

Following the arguments is the keyword AS (IS is a synonym). Then comes the body, which is essentially a PL/SQL block. We have repeated the name of the procedure after the END, but this is optional. However, the DECLARE section should not start with the keyword DECLARE. Rather, following AS we have:

... AS

<local_var_declarations>

BEGIN

    <procedure_body>

END;

.

run;

The run at the end runs the statement that creates the procedure; it does not execute the procedure. To execute the procedure, use another PL/SQL statement, in which the procedure is invoked as an executable statement. For example:

BEGIN addtuple1(99); END;

.

run;

The following procedure also inserts a tuple into T2, but it takes both components as arguments:

CREATE PROCEDURE addtuple2(

    x T2.a%TYPE,

    y T2.b%TYPE)

AS

BEGIN

    INSERT INTO T2(a, b)

    VALUES(x, y);

END addtuple2;

.

run;

Now, to add a tuple (10, ‘abc’) to T2

:

BEGIN

    addtuple2(10, 'abc');

END;

.

run;

The following illustrates the use of an OUT parameter:

CREATE TABLE T3 (

    a INTEGER,

    b INTEGER

);

CREATE PROCEDURE addtuple3(a NUMBER, b OUT NUMBER)

AS

BEGIN

    b := 4;

    INSERT INTO T3 VALUES(a, b);

END;

.

run;

DECLARE

    v NUMBER;

BEGIN

    addtuple3(10, v);

END;

.

run;

Note that assigning values to parameters declared as OUT or INOUT causes the corresponding input arguments to be written. Because of this, the input argument for an OUT or INOUT parameter should be something with an “lvalue”, such as a variable like v in the example above. A constant or a literal argument should not be passed in for an OUT/INOUT parameter.

We can also write functions instead of procedures. In a function declaration, we follow the parameter list by RETURN and the type of the return value:

CREATE FUNCTION <func_name>(<param_list>) RETURN <return_type> AS ...

In the body of the function definition, “RETURN <expression>;” exits from the function and returns the value of <expression>

.

To find out what procedures and functions you have created, use the following SQL query:

select object_type, object_name

from user_objects

where object_type = 'PROCEDURE'

   or object_type = 'FUNCTION';

To drop a stored procedure/function:

drop procedure <procedure_name>;

drop function <function_name>;

show errors procedure <procedure_name>;

Alternatively, you can type, SHO ERR (short for SHOW ERRORS) to see the most recent compilation error.

Note that the location of the error given as part of the error message is not always accurate!

The steps are as follows:

1. We declare a bind variable as follows:

        VARIABLE <name> <type>

   where the type can be only one of three things: NUMBER, CHAR, or CHAR(n).

2. We may then assign to the variable in a following PL/SQL statement, but we must prefix it with a colon.
3. Finally, we can execute a statement

        PRINT :<name>;

   outside the PL/SQL statement

Here is a trivial example, which prints the value 1.

     VARIABLE x NUMBER

     BEGIN

           := 1;

     END;

     .

     run;

     PRINT :x;

PL/SQL TUTORIAL

WHAT IS PL/SQL

pl/sql is the procedural implementation of sql i.e. u can pass sql statements in procedural format using pl/sql. Normal sql does not have any procedural capabilities moreover u can only pass one statement at a time to Oracle Engine. Hence, pl/sql have come up to avoid this limitation. Hence, pl/sql is the structured programming language for oracle. It’s structure is very much similar to any other procedural language such as C or C++

I won’t waste your time in typing out the advantages of pl/sql … u can easily find out in a book.

PL/SQL BLOCK

The pl/sql block contains the following section:–

—–The DECLARE section.
—–The Master BEGIN and END section that contains the EXCEPTION section.

The declare section contains declaration of memory variables, constants, cursors etc. The begin section contains sql executable statements and pl/sql executable statements. The exception section contains code to handle errors that may arise during the execution of the code block. The end declares the end of pl/sql block.

A bit about it’s working. When you typed out the pl/sql block for execution. It is sent to the pl/sql engine, whee procedural statements are executed; and sql statements are sent to the sql executor in the oracle engine. Since pl/sql engine resides in the oracle engine, the codes executes smoothly and efficiently.

PL/SQL DATA-TYPE

This is easy since it includes almost all the data types which u have used in sql such as date, varchar, number, char etc etc… Some of the attributes such as %TYPE is also used. This attribute automatically takes in the default datatype of the sql table from which u have passed the query. We will discuss this later.

Remember in pl/sql a variable name must begin with a character and can be followed by maximum of 29 other characters. Reserved words can’t be used unless enclosed within double quotes. Variables must be seperated from each other by at least one space or by a punctuation mark. You can assign values of operator using := operator. I won’t discuss about logical comparisons operators such as <, > , >=, NOT, TRUE, AND, OR, NULL etc since they r quite easy to understand.

MOST IMPORTANT: HOW TO DISPLAY MESSAGES ON SCREEN —
DBMS_OUTPUT : is a package that includes a number of procedure and functions that accumulate information in a buffer so that it can be retrieved later. These functions can also be used to display messages to the user.
PUT_LINE : Put a piece of information in the package buffer followed by an end-of-line marker. It can also be used to display message to the user. Put_line expects a single parameter of character data type. If used to display a message, it is the message ’string’.
EG: dbms_output.put_line(x);

REMEMBER: To display messages to the user the SERVEROUTPUT should be set to ON. SERVEROUTPUT is a sql*plus environment parameter that displays the information pased as a parameter to the PUT_LINE function.
EG: SET SERVEROUTPUT ON

A bit about comments. A comment can have 2 forms i.e.
– The comment line begins with a double hyphen (–). The entire line will be treated as a comment.
– The C style comment such as /* i am a comment */

CONDITIONAL CONTROL AND ITERATIVE CONTROL AND SEQUENTIAL CONTROL

IF and else…..
IF –Condition THEN
–Action
ELSEIF –Condition THEN
–Action
ELSE
–Action
END IF;

SIMPLE LOOP
loop
– Sequence of statements;
end loop;

the loop ends when u use EXIT WHEN statement –condition

WHILE LOOP
While –condition
loop
–sequence of statements
end loop;

FOR LOOP
FOR i in 1..10
loop
–sequence of statements
end loop;

GOTO (sequential control)
GOTO X;
<< X >>

EXAMPLES

--ADDITION
declare
         a number;
         b number;
         c number;
begin
         a:=&a;
         b:=&b;
         c:=a+b;
         dbms_output.put_line('Sum of ' || a || ' and ' || b || ' is ' || c);

Here & is used to take user input at runtime.....

--SUM OF 100 NUMBERS

Declare
	a number;
	s1 number default 0;
Begin
	a:=1;
	loop
		s1:=s1+a;
		exit when (a=100);
		a:=a+1;
	end loop;
	dbms_output.put_line('Sum between 1 to 100 is '||s1);
End;

--SUM OF odd NUIMBERS USING USER INPUT...for loop
declare
        n number;
        sum1 number default 0;
        endvalue number;
begin
        endvalue:=&endvalue;
        n:=1;
        for n in 1.. endvalue
        loop
             if mod(n,2)=1
             then
                  sum1:=sum1+n;
             end if
        end loop;
        dbms_output.put_line('sum = ' || sum1);
end;

--SUM OF 100 ODD NUMBER .. WHILE LOOP
declare
        n number;
        endvalue number;
        sum1 number default 0;
begin
        endvalue:=&endvalue;
        n:=1;
        while (n < endvalue)
        loop
             sum1:=sum1+n;
             n:=n+2;
        end loop;
        dbms_output.put_line('Sum of odd numbers between 1 and ' || endvalue || ' is ' || sum1);
end;

--CALCULATION OF NET SALARY
declare
        ename varchar2(15);
        basic number;
        da number;
        hra number;
        pf number;
        netsalary number;
begin
        ename:=&ename;
        basic:=&basic;

        da:=basic * (41/100);
        hra:=basic * (15/100);

        if (basic < 3000)
        then
             pf:=basic * (5/100);
        elsif (basic >= 3000 and basic <= 5000)
        then
             pf:=basic * (7/100);
        elsif (basic >= 5000 and basic <= 8000)
        then
             pf:=basic * (8/100);
        else
             pf:=basic * (10/100);
        end if;
        netsalary:=basic + da + hra -pf;
        dbms_output.put_line('Employee name : ' || ename);
        dbms_output.put_line('Providend Fund : ' || pf);
        dbms_output.put_line('Net salary : ' || netsalary);
end;

--MAXIMUM OF 3 NUMBERS
Declare
	a number;
	b number;
	c number;
	d number;
Begin
	dbms_output.put_line('Enter a:');
	a:=&a;
	dbms_output.put_line('Enter b:');
	b:=&b;
	dbms_output.put_line('Enter c:');
	c:=&b;
	if (a>b) and (a>c) then
		dbms_output.putline('A is Maximum');
	elsif (b>a) and (b>c) then
		dbms_output.putline('B is Maximum');
	else
		dbms_output.putline('C is Maximum');
	end if;
End;

--QUERY EXAMPLE--IS SMITH EARNING ENOUGH
declare
        s1 emp.sal %type;
begin
        select sal into s1 from emp
        where ename = 'SMITH';
        if(no_data_found)
        then
           raise_application_error
           (20001,'smith is not present');
        end if;

        if(s1 > 10000)
        then
           raise_application_error
           (20002,'smith is earning enough');
        end if;

        update emp set sal=sal + 500
        where ename='SMITH';
end;

--PRIME NO OR NOT
DECLARE
	no NUMBER (3) := &no;
	a NUMBER (4);
	b NUMBER (2);
BEGIN
	FOR i IN 2..no - 1
	LOOP
		a := no MOD i;
		IF a = 0
		THEN
			GOTO out;
		END IF;
	END LOOP;
	<>
	IF a = 1
	THEN
		DBMS_OUTPUT.PUT_LINE (no || ' is a prime number');
	ELSE
		DBMS_OUTPUT.PUT_LINE (no || ' is not a prime number');
	END IF;
END;

--SIMPLE EXAMPLE OF LOOP STATEMENT I.E. EXIT WHEN
Declare
a number:= 100;
begin
loop
a := a+25;
exit when a=250;
end loop;
dbms_output.put_line (to_Char(a));
end;

--EXAMPLE OF WHILE LOOP
Declare
i number:=0;
j number:= 0;
begin
while i <=100 loop
j := j+1;
i := i +2;
end loop;
dbms_output.put_line(to_char(i));
end;

--EXAMPLE OF FOR LOOP
Declare
begin
for i in 1..10
loop
dbms_output.put_line(to_char(i));
end loop;
end;

--SEQUENTIAL CONTROL GOTO.....
declare
--takes the default datatype of the column of the table price
cost price.minprice%type;
begin
select stdprice into cost from price where prodial in (Select prodid from product where prodese = "shampoo");
if cost > 7000 then
goto Upd;
end if;
<< Upd >>
Update price set minprice = 6999 where prodid=111;
end;

--CALCULATE THE AREA OF A CIRCLE FOR A VALUE OF RADIUS VARYING FROM 3 TO 7. STORE THE RADIUS AND THE CORRESPONDING VALUES OF CALCULATED AREA IN A TABLE AREAS.

Declare
pi constant number(4,2) := 3.14;
radius number(5);
area number(14,2);

Begin
radius := 3;
While radius <=7
Loop
area := pi* power(radius,2);
Insert into areas values (radius, area);
radius:= radius+1;
end loop;
end;

--INVERTING A NUMBER 5639 TO 9365
Declare
given_number varchar(5) := '5639';
str_length number(2);
inverted_number varchar(5);

Begin
str_length := length(given_number);
For cntr in reverse 1..str_length
loop
inverted_number := inverted_number || substr(given_number, cntr, 1);
end loop;
dbms_output.put_line('The Given no is ' || given_number);
dbms_output.put_line('The inverted number is ' || inverted_number);
end;

EXCEPTION HANDLING

Errors in pl/sql block can be handled...error handling refers to the way we handle the errors in pl/sql block so that no
crashing stuff of code takes place...This is exactly the same as we do in C++ or java..right!!
There are two type:
===> predefined exceptions
===> user defined exceptions
The above 2 terms are self explanatory

predefined exceptions:

No-data-found            ==   when no rows are returned
Cursor-already-open ==   when a cursor is opened in advance
Dup-val-On-index      ==   for duplicate entry of index..
Storage-error             ==   if memory is damaged
Program-error            ==   internal problem in pl/sql
Zero-divide                 ==   divide by zero
invalid-cursor             ==   if a cursor is not open and u r trying to close it
Login-denied              ==   invalid user name or password
Invalid-number          ==   if u r inserting a string datatype for a number datatype which is already declared
Too-many-rows         ==   if more rows r returned by select statement

SYNTAX


begin
sequence of statements;
exception
when --exception name then
sequence of statements;
end;

EXAMPLES

--When there is no data returned by row
declare
price item.actualprice%type;
begin
Select actual price into price from item where qty=888;
when no-data-found then
dbms_output.put_line('item missing');
end;

--EXAMPLE OF USER DEFINED EXCEPTION
DECLARE
 e_rec emp%ROWTYPE;
 e1 EXCEPTION;
 sal1 emp.sal%TYPE;
BEGIN
 SELECT sal INTO sal1 FROM emp WHERE deptno = 30 AND ename = 'John';
 IF sal1 < 5000 THEN
  RAISE e1;
  sal1 := 8500;
  UPDATE emp SET sal = sal1 WHERE deptno = 30 AND ename = 'John';
 END IF;
 EXCEPTION
  WHEN no_data_found THEN
   RAISE_APPLICATION_ERROR (-20001, 'John is not there.');
  WHEN e1 THEN
   RAISE_APPLICATION_ERROR (-20002, 'Less Salary.');
END;

--EXAMPLE OF RAISE-APPLICATION-ERROR... THIS IS YOUR OWN ERROR STATEMENT...U RAISE
--YOUR OWN ERROR

Declare
s1 emp.sal %type;
begin
select sal into s1 from emp where ename='SOMDUTT';
if(no-data-found) then
raise_application_error(20001, 'somdutt is not there');
end if;
if(s1 > 10000) then
raise_application_error(20002, 'somdutt is earing a lot');
end if;
update emp set sal=sal+500 where ename='SOMDUTT';
end;

--INTERESTING EG OF USER DEFINED EXCEPTIONS
Declare
zero-price exception;
price number(8);
begin
select actualprice into price from item where ordid =400;
if price=0 or price is null then
raise zero-price;
end if;
exception
when zero-price then
dbms_output.put_line('raised xero-price exception');
end;

CURSORS

Cursor is a work area in pl/sql which is used by sql server used to store the result of a query. Each column value is pointed using pointer. You can independently manipulate cursor values. A bit about it’s working….. suppose u ask for a query stored in the server … at first a cursor consisting of query result is created in server…now the cursor is transferred to the client where again cursor is created and hence the result is displayed……

Cursors are of 2 types: implicit and explicit…….implicit cursors are created by oracle engine itself while explicit cursors are created by the users……cursors are generally used in such a case when a query returns more than one rows….normal pl/sql returning more than one rows givens error but using cursor this limitation can be avoided….so cursors are used….

cursor attributes

%ISOPEN   == returns true if ursor is open, false otherwise
%FOUND   == returns true if recod was fetched successfully, false otherwise
%NOTFOUND  == returns true if record was not fetched successfully, false otherwise
%ROWCOUNT == returns number of records processed from the cursor.

Very important: Cursor can be controlled using following 3 control statements. They are Open, Fetch, Close…..open statement identifies the active set…i.e. query returned by select statement…close statement closes the cursor…and fetch statement fetches rows into the variables…Cursors can be made into use using cursor for loop and fetch statement…we will see the corresponding examples…

EXAMPLES

--EXAMPLE OF SQL%FOUND (IMPLICIT CURSORS)
begin
update employee set salary=salary *0.15
where emp_code = &emp_code;
if sql%found then
dbms_output.put_line('employee record modified successfully');
else
dbms_output.put_line('employee no does not exist');
end if;
end;

--EXAMPLE FOR SQL%NOTFOUND (IMPLICIT CURSORS)
begin
update employee set salary = salary*0.15 where emp_code = &emp_code;
if sql%notfound then
dbms_output.put_line('employee no . does not exist');
else
dbms_output.put_line('employee record modified successfully');
end if;
end;

--EXAMPLE FOR SQL%ROWCOUNT (IMPLICIT CURSORS)
declare
rows_affected char(4);
begin
update employee set salary = salary*0.15 where job='programmers';
rows_affected := to_char(sql%rowcount);
if sql%rowcount > 0 then
dbms_output.put_line(rows_affected || 'employee records modified successfully');
else
dbms_output.put_line('There are no employees working as programmers');
end if;
end;

Syntax of explicit cursor: Cursor cursorname is sql select statement;
Syntax of fetch : fetch cursorname into variable1, variable2…;
Syntax of close; close cursorname;
Syntax of open cursor; open cursorname;

--EXPLICIT CURSOR EG
DECLARE
	CURSOR c1 is SELECT * FROM emp;
	str_empno emp.empno%type;
	str_ename emp.ename%type;
	str_job emp.job%type;
	str_mgr emp.mgr%type;
	str_hiredate emp.hiredate%type;
	str_sal emp.sal%type;
	str_comm emp.comm%type;
	str_deptno emp.deptno%type;
	rno number;
BEGIN
	rno := &rno;
	FOR e_rec IN c1
	LOOP
		IF c1%rowcount = rno THEN
			DBMS_OUTPUT.PUT_LINE (str_empno || ' ' || str_ename || ' ' || str_job || ' ' || str_mgr || ' ' || str_hiredate || ' ' || str_sal || ' ' || str_comm || ' ' || str_deptno);
		END IF;
	END LOOP;
END;

--ANOTHER EG DISPLAYING VALUE OF A TABLE
DECLARE
	CURSOR c1 IS SELECT  * FROM emp;
	e_rec emp%rowtype;
BEGIN
	OPEN c1;
	LOOP
		FETCH c1 INTO e_rec;
		DBMS_OUTPUT.PUT_LINE('Number: ' || ' ' || e_rec.empno);
		DBMS_OUTPUT.PUT_LINE('Name  : ' || ' ' || e_rec.ename);
		DBMS_OUTPUT.PUT_LINE('Salary: ' || ' ' || e_rec.sal);
		EXIT WHEN c1%NOTFOUND;
	END LOOP;
	CLOSE c1;
END;

-- Display details of Highest 10 salary paid employee

DECLARE
	CURSOR c1 IS SELECT  * FROM emp ORDER BY sal DESC;
	e_rec emp%rowtype;
BEGIN
	FOR e_rec IN c1
	LOOP
		DBMS_OUTPUT.PUT_LINE('Number: ' || ' ' || e_rec.empno);
		DBMS_OUTPUT.PUT_LINE('Name  : ' || ' ' || e_rec.ename);
		DBMS_OUTPUT.PUT_LINE('Salary: ' || ' ' || e_rec.sal);
		EXIT WHEN c1%ROWCOUNT >= 10;
	END LOOP;
END;

-- EXAMPLE OF CURSOR FOR LOOP
declare cursor c1 is select * from somdutt;
begin
for outvariable in c1
loop
exit when c1%notfound;
if outvariable.age < 21 then
dbms_output.put_line(outvariable.age || ' ' || outvariable.name);
end if;
end loop;
end;

--ref STRONG CURSORS
DECLARE
	TYPE ecursor IS REF CURSOR RETURN emp%ROWTYPE;
	ecur ecursor;
	e_rec emp%ROWTYPE;
	dn NUMBER;
BEGIN
	dn := &deptno;
	OPEN ecur FOR SELECT * FROM emp WHERE deptno = dn;
	FOR e_rec IN ecur
	LOOP
		DBMS_OUTPUT.PUT_LINE ('Employee No    : ' || e_rec.empno);
		DBMS_OUTPUT.PUT_LINE ('Employee Salary: ' || e_rec.salary);
	END LOOP;
END;

--REF WEAK CURSORS
DECLARE
	TYPE tcursor IS REF CURSOR;
	tcur tcursor;
	e1 emp%ROWTYPE;
	d1 dept%ROWTYPE;
	tname VARCHAR2(20);
BEGIN
	tname := &tablename;
	IF tname = 'emp' THEN
		OPEN tcur FOR SELECT * FORM emp;
		DBMS_OUTPUT.PUT_LINE ('Emp table opened.');
		close tcur;
		DBMS_OUTPUT.PUT_LINE ('Emp table closed.');
	ELSE IF tname = 'dept' THEN
		OPEN tcur FOR SELECT * FROM dept;
		DBMS_OUTPUT.PUT_LINE ('Dept table opened.');
		close tcur;
		DBMS_OUTPUT.PUT_LINE ('Emp table closed.');
	ELSE
		RAISE_APPLICATION_ERROR (-20004, 'Table name is wrong');
	END IF;
END;

--CURSOR FOR LOOP WITH PARAMETERS
Declare
Cursor c1(Dno number) is select * from emp where deptno = dno;
begin
for empree in c1(10) loop;
dbms_output.put_line(empree.ename);
end loop;
end;

TRIGGERS

Trigger is a stored procedure which is called implicitly by oracle engine whenever a insert, update or delete statement is fired.

Advantages of database triggers:
—> Data is generated on it’s own
—> Replicate table can be maintained
—> To enforce complex integrity contraints
—> To edit data modifications
—> To autoincrement a field
etc..

Syntax: Create or replace trigger –triggername– [before/after] [insert/pdate/delete] on –tablename– [for each satement/ for each row] [when --condition--] plus..begin.and exception

Triggers are of following type: before or after trigger ….and for each row and for each statement trigger… before trigger is fired before insert/update/delete statement while after trigger is fired after insert/update/delete statement…for each row and for each statements triggers are self explainatory..

EXAMPLE

— A database trigger that allows changes to employee table only during the business hours(i.e. from 8 a.m to 5.00 p.m.) from monday to saturday. There is no restriction on viewing data from the table -CREATE OR REPLACE TRIGGER Time_Check BEFORE INSERT OR UPDATE OR DELETE ON EMP BEGIN IF TO_NUMBER(TO_CHAR(SYSDATE,’hh24′)) < 10 OR TO_NUMBER(TO_CHAR(SYSDATE,’hh24′)) >= 17 OR TO_CHAR(SYSDATE,’DAY’) = ‘SAT’ OR TO_CHAR(SYSDATE,’DAY’) = ‘SAT’ THEN RAISE_APPLICATION_ERROR (-20004,’YOU CAN ACCESS ONLY BETWEEN 10 AM TO 5 PM ON MONDAY TO FRIDAY ONLY.’); END IF; END;

Remember trigger can be dropped using Drop Trigger triggername ; statement…

PROCEDURES AND FUNCTIONS

procedure is a subprogram…which consists of a set of sql statement. Procedures are not very different from functions. A procedure or function is a logically grouped set of SQL and PL/SQL statements that perform a specific task. A stored procedure or function is a named pl/sql code block that have been compiled and stored in one of the oracle engines’s system tables.

To make a procedure or function dynamic either of them can be passed parameters before execution. A procedure or function can then change the way it works depending upon the parameters passed prior to its execution.

Procedures and function are made up of a declarative part, an executable part and an optional exception-handling part

A declaration part consists of declarations of variables. A executable part consists of the logic i.e. sql statements….and exception handling part handles any error during run-time

The oracle engine performs the following steps to execute a procedure or funtion….Verifies user access, Verifies procedure or funtion validity and executes the procedure or function. Some of the advantages of using procedures and functions are: security, performance, memory allocation, productivity, integrity.

Most important the difference between procedures and functions: A function must return a value back to the caller. A function can return only one value to the calling pl/sql block. By defining multiple out parameters in a procedure, multiple values can be passed to the caller. The out variable being global by nature, its value is accessible by any pl/sql code block including the calling pl/sql block.

Syntax for stored procedure:
CREATE OR REPLACE PROCEDURE [schema] procedurename (argument { IN, OUT, IN OUT} data type, ..) {IS, AS}
variable declarations; constant declarations; BEGIN
pl/sql subprogram body;
EXCEPTION
exception pl/sql block;
END;

Syntax for stored function:
CREATE OR REPLACE FUNCTION[schema] functionname(argument IN data type, ..) RETURN data type {IS, AS}
variable declarations; constant declarations; BEGIN
pl/sql subprogram body;
EXCEPTION
exception pl/sql block;
END;

The above syntax i think is self explainatory…but i will give u some details…IN : specifies that a value for the argument must be specified when calling the procedure or function. argument : is the name of an argument to the procedure or function. parentheses can be omitted if no arguments are present. OUT : specifies that the procedure passes a value for this argument back to its calling environment after execution. IN OUT : specifies that a value for the argument must be specified when calling the procedure and that the procedure passes a value for this argument back to its calling environment after execution. By default it takes IN. Data type : is the data type of an argument.

EXAMPLES

--PROCEDURE USING NO ARGUMENT..AND USING CURSOR
CREATE OR REPLACE PROCEDURE P2 IS
cursor cur1 is select * from emp;
begin
for erec in cur1
loop
dbms_output.put_line(erec.ename);
end loop;
end;

--PROCEDURE USING ARGUMENT
CREATE OR REPLACE PROCEDURE ME( X IN NUMBER) IS
BEGIN
dbms_output.put_line(x*x);
end;

sql> exec me(3);

--FUNCTION using argument
CREATE OR REPLACE FUNCTION RMT(X IN NUMBER) RETURN NUMBER IS
BEGIN
dbms_output.put_line(x*x);
--return (x*x);
end;

(make a block like this to run it.....)
begin
dbms_output.put_line(rmt(3));
end;

--CREATE A PROCEDURE THAT DELETE ROWS FROM ENQUIRY
--WHICH ARE 1 YRS BEFORE

Create or replace procedure myprocedure is begin
delete from enquiry where enquirydate <= sysdate - 1;
end;

--CREATE A PROCEDURE THAT TAKES ARGUMENT STUDENT NAME,
--AND FIND OUT FEES PAID BY THAT STUDENT

CREATE or REPLACE procedure me (namee in varchar) is
cursor c1 is select a.feespaiddate from feespaid a, enrollment b, enquiry c
where
c.enquiryno = b.enquiryno and
a.rollno = b.rollno and
c.fname = namee;
begin
for erec in c1
loop
dbms_output.put_line(erec.feespaiddate);
end loop;
end;

--SUM OF 2 NOS
CREATE or replace procedure p1 is
Declare
 a number;
 b number;
 c number;
Begin
 a:=50;
 b:=89;
 c:=a+b;
 dbms_output.put_line('Sum of '||a||' and '||b||' is '||c);
End;

--DELETION PROCEDURE
create or replace procedure myproc is
begin
delete from enquiry where fname='somdutt';
end;

--IN and OUT procedure example
Create or replace procedure lest ( a number, b out number) is
identify number;
begin
select ordid into identity from item where
itemid = a;
if identity < 1000 then
b := 100;
end if;
end l

--in out parameter eg
Create or replace procedure sample ( a in number, b in out number) is
identity number;
begin
select ordid, prodid into identity, b from item where itemid=a;
if b<600 then
b := b + 100;
end if;
end;

now procedure is called by passing parameter

declare
a number;
b number;
begin
sample(3000, b)
dbms_output.put_line(1th value of b is 11 b);
end ;

--SIMILAR EG AS BEFORE
create or replace procedure getsal( sal1 in out number) is
begin
select sal into sal1 from emp
where empno =  sal1;
end ;

now use the above in plsql block

declare
sal1 number := 7999;
begin
getsal(sal1);
dbms_output.put_line('The employee salary is' || sal1);
end ;

u can make a procedure and functions similarly…..also if u wanna drop a function then use drop function functionname and for procedure use drop procedure procedurename

PACKAGES

A package is an oracle object, which holds other objects within it. Objects commonly held within a package are procedures, functions, variables, constants, cursors and exceptions. Packages in plsql is very much similar to those packages which we use in JAVA……yeah!! java packages holds numerous classes..right!!!…

A package has 2 parts….. package specification and package body

A package specification part consists of all sort of declaration of functions and procedures while package body consists of codings and logic of declared functions and procedures…

EXAMPLE

--SIMPLEST EG

--specification
create or replace package pack2 is
function rmt(x in number) return number;
procedure rmt1(x in number);
end;

--body
create or replace package body pack2 is
function rmt(x in number) return number is
begin
return (x*x);
end;

procedure rmt1(x in number) is
begin
dbms_output.put_line(x*x);
end;
end;

(how to run.....)
exec packagename.procedurename
i.e.
exec pack2.rmt1(3);

As shown above u can put in complicated procedures and functions inside the package…I have just shown a simple example…u can easily modify the above code to fit your requirement……Just try out packages which includes cursors, procedures and functions..etc..Remeber pl/sql supports overloading…i.e. u can use the same function or procedure name in your application but with different no or type of arguments..

Q. 1

Which colour is used to indicate instance methods in the standard “javadoc” format documentation:

A. blue

B. red

C. purple

D. orange

Select the most appropriate answer.

Q. 2

What is the correct ordering for the import, class and package declarations when found in a single file?

A. package, import, class

B. class, import, package

C. import, package, class

D. package, class, import

Select the most appropriate answer.

Q. 3

Which methods can be legally applied to a string object?

A. equals(String)

B. equals(Object)

C. trim()

D. round()

E. toString()

Select all correct answers.

Q. 4

What is the parameter specification for the public static void main method?

A. String args []

B. String [] args

C. Strings args []

D. String args

Select all correct answers.

Q. 5

What does the zeroth element of the string array passed to the public static void main method contain?

A. The name of the program

B. The number of arguments

C. The first argument if one is present

Select the most appropriate answer.

Q. 6

Which of the following are Java keywords?

A. goto

B. malloc

C. extends

D. FALSE

Select all correct answers

Q. 7

What will be the result of compiling the following code:

public class Test {

public static void main (String args []) {

int age;

age = age + 1;

System.out.println(”The age is ” + age);

}

}

A. Compiles and runs with no output

B. Compiles and runs printing out The age is 1

C. Compiles but generates a runtime error

D. Does not compile

E. Compiles but generates a compile time error

Select the most appropriate answer.

Q. 8

Which of these is the correct format to use to create the literal char value a?

A. �a�

B. “a”

C. new Character(a)

D. \000a

Select the most appropriate answer.

Q. 9

What is the legal range of a byte integral type?

A. 0 - 65, 535

B. (�128) � 127

C. (�32,768) � 32,767

D. (�256) � 255

Select the most appropriate answer.

Q. 10

Which of the following is illegal:

A. int i = 32;

B. float f = 45.0;

C. double d = 45.0;

Select the most appropriate answer.

Q. 11

What will be the result of compiling the following code:

public class Test {

static int age;

public static void main (String args []) {

age = age + 1;

System.out.println(”The age is ” + age);

}

}

A. Compiles and runs with no output

B. Compiles and runs printing out The age is 1

C. Compiles but generates a runtime error

D. Does not compile

E. Compiles but generates a compile time error

Select the most appropriate answer.

Q. 12

Which of the following are correct?

A. 128 >> 1 gives 64

B. 128 >>> 1 gives 64

C. 128 >> 1 gives �64

D. 128 >>> 1 gives �64

Select all correct answers

Q. 13

Which of the following return true?

A. “john” == “john”

B. “john”.equals(”john”)

C. “john” = “john”

D. “john”.equals(new Button(”john”))

Select all correct answers.

Q. 14

Which of the following do not lead to a runtime error?

A. “john” + ” was ” + ” here”

B. “john” + 3

C. 3 + 5

D. 5 + 5.5

Select all correct answers.

Q. 15

Which of the following are so called “short circuit” logical operators?

A. &

B. ||

C. &&

D. |

Select all correct answers.

Q. 16

Which of the following are acceptable?

A. Object o = new Button(”A”);

B. Boolean flag = true;

C. Panel p = new Frame();

D. Frame f = new Panel();

E. Panel p = new Applet();

Select all correct answers.

Q. 17

What is the result of compiling and running the following code:

public class Test {

static int total = 10;

public static void main (String args []) {

new Test();

}

public Test () {

System.out.println(”In test”);

System.out.println(this);

int temp = this.total;

if (temp > 5) {

System.out.println(temp);

}

}

}

A. The class will not compile

B. The compiler reports and error at line 2

C. The compiler reports an error at line 9

D. The value 10 is one of the elements printed to the standard output

E. The class compiles but generates a runtime error

Select all correct answers.

Q 18

Which of the following is correct:

A. String temp [] = new String {”j” “a” “z”};

B. String temp [] = { “j ” ” b” “c”};

C. String temp = {”a”, “b”, “c”};

D. String temp [] = {”a”, “b”, “c”};

Select the most appropriate answer.

Q. 19

What is the correct declaration of an abstract method that is intended to be public:

A. public abstract void add();

B. public abstract void add() {}

C. public abstract add();

D. public virtual add();

Select the most appropriate answer.

Q. 20

Under what situations do you obtain a default constructor?

A. When you define any class

B. When the class has no other constructors

C. When you define at least one constructor

Select the most appropriate answer.

Q. 21

Given the following code:

public class Test {

�

}

Which of the following can be used to define a constructor for this class:

A. public void Test() {�}

B. public Test() {�}

C. public static Test() {�}

D. public static void Test() {�}

Select the most appropriate answer.

Q. 22

Which of the following are acceptable to the Java compiler:

A. if (2 == 3) System.out.println(”Hi”);

B. if (2 = 3) System.out.println(”Hi”);

C. if (true) System.out.println(”Hi”);

D. if (2 != 3) System.out.println(”Hi”);

E. if (aString.equals(”hello”)) System.out.println(”Hi”);

Select all correct answers.

Q. 23

Assuming a method contains code which may raise an Exception (but not a RuntimeException), what is the correct way for a method to indicate that it expects the caller to handle that exception:

A. throw Exception

B. throws Exception

C. new Exception

D. Don’t need to specify anything

Select the most appropriate answer.

Q. 24

What is the result of executing the following code, using the parameters 4 and 0:

public void divide(int a, int b) {

try {

int c = a / b;

} catch (Exception e) {

System.out.print(”Exception “);

} finally {

System.out.println(”Finally”);

}

A. Prints out: Exception Finally

B. Prints out: Finally

C. Prints out: Exception

D. No output

Select the most appropriate answer.

Q.25

Which of the following is a legal return type of a method overloading the following method:

public void add(int a) {�}

A. void

B. int

C. Can be anything

Select the most appropriate answer.

Q.26

Which of the following statements is correct for a method which is overriding the following method:

public void add(int a) {�}

A. the overriding method must return void

B. the overriding method must return int

C. the overriding method can return whatever it likes

Select the most appropriate answer.

Q. 27

Given the following classes defined in separate files:

class Vehicle {

public void drive() {

System.out.println(”Vehicle: drive”);

}

}

class Car extends Vehicle {

public void drive() {

System.out.println(”Car: drive”);

}

}

public class Test {

public static void main (String args []) {

Vehicle v;

Car c;

v = new Vehicle();

c = new Car();

v.drive();

c.drive();

v = c;

v.drive();

}

}

What will be the effect of compiling and running this class Test?

A. Generates a Compiler error on the statement v= c;

B. Generates runtime error on the statement v= c;

C. Prints out:

Vehicle: drive

Car: drive

Car: drive

D. Prints out:

Vehicle: drive

Car: drive

Vehicle: drive

Select the most appropriate answer.

Q. 28

Where in a constructor, can you place a call to a constructor defined in the super class?

A. Anywhere

B. The first statement in the constructor

C. The last statement in the constructor

D. You can’t call super in a constructor

Select the most appropriate answer.

Q. 29

Which variables can an inner class access from the class which encapsulates it?

A. All static variables

B. All final variables

C. All instance variables

D. Only final instance variables

E. Only final static variables

Select all correct answers.

Q. 30

What class must an inner class extend:

A. The top level class

B. The Object class

C. Any class or interface

D. It must extend an interface

Select the most appropriate answer.

Question 11.

public class AQuestion{
	private int i = giveMeJ();
	private int j = 10;
	private int giveMeJ(){
		return j;
	}
	public static void main(String args[]){
		System.out.println((new AQuestion()).i);
	}
}

Answers
1. Compiler error complaining about access restriction of private variables of AQuestion.
2. Compiler error complaining about forward referencing.
3. No Compilation error - The output is 0;
4. No Compilation error - The output is 10;

Question 12.

public class AQuestion{
	public static void main(String args[]){
		System.out.println("Before Try");
		try{
		}
		catch(Throwable t){
			System.out.println("Inside Catch");
		}
			System.out.println("At the End");
		}
}

1. Compiler error complaining about the catch block, where no Throwable object can ever be thrown.
2. Compiler error - Throwable Object can not be caught, only Exceptions must be caught.
3. No compiler error. The lines “Before Try” and “At the end” are printed on the screen.

Question 13.

public class AQuestion{
	public static void main(String args[]){
		System.out.println("Before Try");
		try{
		}
		catch(java.io.IOException t){
			System.out.println("Inside Catch");
		}
			System.out.println("At the End");
	}
}

1. Compiler error complaining about the catch block where no IOException object can ever be thrown.
2. Compiler error - IOException not found. It must be imported in the first line of the code.
3. No compiler error. The lines “Before Try” and “At the end” are printed on the screen.

Question 14.
The class java.lang.Exception
i. Is public
ii. Extends Throwable
iii. Implements Throwable
iv. Is serializable

Question 15.
Read this piece of code carefully

if("String".trim() == "String".trim())
	System.out.println("Equal");
else
	System.out.println("Not Equal");

Answers
1. the code will compile an print “Equal”.
2. the code will compile an print “Not Equal”.
3. the code will cause a compiler error

Question 16.
Read this piece of code carefully

if( "STRING".toUpperCase() == "STRING")
	System.out.println("Equal");
else
	System.out.println("Not Equal");

Answers
1. the code will compile an print “Equal”.
2. the code will compile an print “Not Equal”.
3. the code will cause a compiler error

Question 17.
The following lines of code
byte b = 0;
b += 1;
1. results in b having the value 1.
2. causes a compiler error.
3. will require a cast (byte) before 1.

Question 18.
The following express
char c = -1;
1. will cause a compiler error as the range of character is between 0 and 2^16 - 1. Will request for an explicit cast.
2. will not cause a compiler error and c will have the value -1;
3. c will not represent any ASCII character.
4. c will still be a Unicode character.

Question 19.
Which of the following statements are true?
1. A method can throw an Exception
2. A method can return an Exception

Question 20.
All the wrapper classes (Integer, Boolean, Float, Short, Long, Double and Character)
1. are public
2. are serializable
3. are immutatable
4. extend java.lang.Number
5. are final

Question 1.
Read this piece of code carefully

if("String".toString() == "String")
	System.out.println("Equal");
else
	System.out.println("Not Equal");

Answers
1. the code will compile an print “Equal”.
2. the code will compile an print “Not Equal”.
3. the code will cause a compiler error.

Question 2.
Read this piece of code carefully

if("String".trim() == "String")
	System.out.println("Equal");
else
	System.out.println("Not Equal");

Answers
1. the code will compile an print “Equal”.
2. the code will compile an print “Not Equal”.
3. the code will cause a compiler error

Question 3.
Read the code below. Will be the result of attempting to compile and run the code below.

public class AQuestion {
	public void method(Object o){
		System.out.println("Object Verion");
	}
	public void method(String s){
		System.out.println("String Version");
	}
	public static void main(String args[]){
		AQuestion question = new AQuestion();
		question.method(null);
	}
}

Answers
1. The code does not compile.
2. The code compiles cleanly and shows “Object Version”.
3. The code compiles cleanly and shows “String Version”
4. The code throws an Exception at Runtime.

Question 4.
Read the code below. Will be the result of attempting to compile and run the code below.

public class AQuestion{
	public void method(StringBuffer sb){
		System.out.println("StringBuffer Verion");
	}
	public void method(String s){
		System.out.println("String Version");
	}
	public static void main(String args[]){
		AQuestion question = new AQuestion();
		question.method(null);
	}
}

Answers
1. The code does not compile.
2. The code compiles cleanly and shows “StringBuffer Version”.
3. The code compiles cleanly and shows “String Version”
4. The code throws an Exception at Runtime.

Question 5.
Read the following code below.

public interface AQuestion{
	public abstract void someMethod() throws Exception;
}

A Class implementing this interface should
1. Necessarily be an abstract class.
2. Should have the method public abstract void someMethod();
3. Should have the method public void someMethod() which has to throw an exception which is a subclass of java.lang.Exception.
4. Should have the method public void someMethod() which need not throw an Exception.

Question 6.
An Interface can never be private or protected.

Answers
True
False

Question 7.
A Vector class in jdk 1.2

1. is public
2. is final
3. implements java.util.List
4. is serializable
5. has only One constructor

Question 8.
A String Class

1. is final
2. is public
3. is serializable
4. has a constructor which takes a StingBuffer Object as an Argument

Question 9.

public interface AQuestion{
	void someMethod();
}

The class which implements AQuestion
1. Should have someMethod which must necessarily be public.
2. Should have someMethod which could be “friendly” or public
3. Should have someMethod which should not throw any checked exceptions.
4. Should have someMethod which cannot be sychronized as sychronized is not in the signature of the interface defination

Question 10.

public class AQuestion{
	private int i = j;
	private int j = 10;
	public static void main(String args[]){
		System.out.println((new AQuestion()).i);
	}
}

Answers 

1. Compiler error complaining about access restriction of private variables of AQuestion. 

2. Compiler error complaining about forward referencing. 

3. No error - The output is 0; 

4. No error - The output is 10;

* Develop code that declares an interface. Develop code that implements or extends one or more interfaces. Develop code that declares an abstract class. Develop code that extends an abstract class.

* Develop code that declares, initializes, and uses primitives, arrays, enums, and objects as static, instance, and local variables. Also, use legal identifiers for variable names.

* Develop code that declares both static and non-static methods, and - if appropriate - use method names that adhere to the JavaBeans naming standards. Also develop code that declares and uses a variable-length argument list.

* Given a code example, determine if a method is correctly overriding or overloading another method, and identify legal return values (including covariant returns), for the method.

* Given a set of classes and superclasses, develop constructors for one or more of the classes. Given a class declaration, determine if a default constructor will be created, and if so, determine the behavior of that constructor. Given a nested or non-nested class listing, write code to instantiate the class.

Section 2: Flow Control

* Develop code that implements an if or switch statement; and identify legal argument types for these statements.

* Develop code that implements all forms of loops and iterators, including the use of for, the enhanced for loop (for-each), do, while, labels, break, and continue; and explain the values taken by loop counter variables during and after loop execution.

* Develop code that makes use of assertions, and distinguish appropriate from inappropriate uses of assertions.

* Develop code that makes use of exceptions and exception handling clauses (try, catch, finally), and declares methods and overriding methods that throw exceptions.

* Recognize the effect of an exception arising at a specified point in a code fragment. Note that the exception may be a runtime exception, a checked exception, or an error.

* Recognize situations that will result in any of the following being thrown: ArrayIndexOutOfBoundsException,ClassCastException, IllegalArgumentException, IllegalStateException, NullPointerException, NumberFormatException, AssertionError, ExceptionInInitializerError, StackOverflowError or NoClassDefFoundError. Understand which of these are thrown by the virtual machine and recognize situations in which others should be thrown programatically.

Section 3: API Contents

* Develop code that uses the primitive wrapper classes (such as Boolean, Character, Double, Integer, etc.), and/or autoboxing & unboxing. Discuss the differences between the String, StringBuilder, and StringBuffer classes.

* Given a scenario involving navigating file systems, reading from files, or writing to files, develop the correct solution using the following classes (sometimes in combination), from java.io: BufferedReader,BufferedWriter, File, FileReader, FileWriter and PrintWriter.

* Develop code that serializes and/or de-serializes objects using the following APIs from java.io: DataInputStream, DataOutputStream, FileInputStream, FileOutputStream, ObjectInputStream, ObjectOutputStream and Serializable.

* Use standard J2SE APIs in the java.text package to correctly format or parse dates, numbers, and currency values for a specific locale; and, given a scenario, determine the appropriate methods to use if you want to use the default locale or a specific locale. Describe the purpose and use of the java.util.Locale class.

* Write code that uses standard J2SE APIs in the java.util and java.util.regex packages to format or parse strings or streams. For strings, write code that uses the Pattern and Matcher classes and the String.split method. Recognize and use regular expression patterns for matching (limited to: . (dot), * (star), + (plus), ?, \d, \s, \w, [], ()). The use of *, +, and ? will be limited to greedy quantifiers, and the parenthesis operator will only be used as a grouping mechanism, not for capturing content during matching. For streams, write code using the Formatter and Scanner classes and the PrintWriter.format/printf methods. Recognize and use formatting parameters (limited to: %b, %c, %d, %f, %s) in format strings.

Section 4: Concurrency

* write code to define, instantiate, and start new threads using both java.lang.Thread and java.lang.Runnable.

* Recognize the states in which a thread can exist, and identify ways in which a thread can transition from one state to another.

* Given a scenario, write code that makes appropriate use of object locking to protect static or instance variables from concurrent access problems.

* Given a scenario, write code that makes appropriate use of wait, notify, or notifyAll.

Section 5: OO Concepts

* Develop code that implements tight encapsulation, loose coupling, and high cohesion in classes, and describe the benefits.

* Given a scenario, develop code that demonstrates the use of polymorphism. Further, determine when casting will be necessary and recognize compiler vs. runtime errors related to object reference casting.

* Explain the effect of modifiers on inheritance with respect to constructors, instance or static variables, and instance or static methods.

* Given a scenario, develop code that declares and/or invokes overridden or overloaded methods and code that declares and/or invokes superclass, overridden, or overloaded constructors.

* Develop code that implements “is-a” and/or “has-a” relationships.

Section 6: Collections / Generics

* Given a design scenario, determine which collection classes and/or interfaces should be used to properly implement that design, including the use of the Comparable interface.

* Distinguish between correct and incorrect overrides of corresponding hashCode and equals methods, and explain the difference between == and the equals method.

* Write code that uses the generic versions of the Collections API, in particular, the Set, List, and Map interfaces and implementation classes. Recognize the limitations of the non-generic Collections API and how to refactor code to use the generic versions.

* Develop code that makes proper use of type parameters in class/interface declarations, instance variables, method arguments, and return types; and write generic methods or methods that make use of wildcard types and understand the similarities and differences between these two approaches.

* Use capabilities in the java.util package to write code to manipulate a list by sorting, performing a binary search, or converting the list to an array. Use capabilities in the java.util package to write code to manipulate an array by sorting, performing a binary search, or converting the array to a list. Use the java.util.Comparator and java.lang.Comparable interfaces to affect the sorting of lists and arrays. Furthermore, recognize the effect of the “natural ordering” of primitive wrapper classes and java.lang.String on sorting.

Section 7: Fundamentals

* Given a code example and a scenario, write code that uses the appropriate access modifiers, package declarations, and import statements to interact with (through access or inheritance) the code in the example.

* Given an example of a class and a command-line, determine the expected runtime behavior.

* Determine the effect upon object references and primitive values when they are passed into methods that perform assignments or other modifying operations on the parameters.

* Given a code example, recognize the point at which an object becomes eligible for garbage collection, and determine what is and is not guaranteed by the garbage collection system. Recognize the behaviors of System.gc and finalization.

* Given the fully-qualified name of a class that is deployed inside and/or outside a JAR file, construct the appropriate directory structure for that class. Given a code example and a classpath, determine whether the classpath will allow the code to compile successfully.

* Write code that correctly applies the appropriate operators including assignment operators (limited to: =, +=, -=), arithmetic operators (limited to: +, -, *, /, %, ++, –), relational operators (limited to: <, <=, >, >=, ==, !=), the instanceof operator, logical operators (limited to: &, |, ^, !, &&, ||), and the conditional operator ( ? : ), to produce a desired result. Write code that determines the equality of two objects or two primitives.

Section 2: Flow control, Assertions, and Exception Handling

* Write code using if and switch statements and identify legal argument types for these statements.
* Write code using all forms of loops including labeled and unlabeled, use of break and continue, and state the values taken by loop counter variables during and after loop execution.
* Write code that makes proper use of exceptions and exception handling clauses (try, catch, finally) and declares methods and overriding methods that throw exceptions.
* Recognize the effect of an exception arising at a specified point in a code fragment. Note: The exception may be a runtime exception, a checked exception, or an error (the code may include try, catch, or finally clauses in any legitimate combination).
* Write code that makes proper use of assertions, and distinguish appropriate from inappropriate uses of assertions.
* Identify correct statements about the assertion mechanism.

Section 3: Garbage Collection

* State the behavior that is guaranteed by the garbage collection system.
* Write code that explicitly makes objects eligible for garbage collection.
* Recognize the point in a piece of source code at which an object becomes eligible for garbage collection.

Section 4: Language Fundamentals

* Identify correctly constructed package declarations, import statements, class declarations (of all forms including inner classes) interface declarations, method declarations (including the main method that is used to start execution of a class), variable declarations, and identifiers.
* Identify classes that correctly implement an interface where that interface is either java.lang.Runnable or a fully specified interface in the question.
* State the correspondence between index values in the argument array passed to a main method and command line arguments.
* Identify all Java programming language keywords. Note: There will not be any questions regarding esoteric distinctions between keywords and manifest constants.
* State the effect of using a variable or array element of any kind when no explicit assignment has been made to it.
* State the range of all primitive formats, data types and declare literal values for String and all primitive types using all permitted formats bases and representations.

Section 5: Operators and Assignments

* Determine the result of applying any operator (including assignment operators and instance of) to operands of any type class scope or accessibility or any combination of these.
* Determine the result of applying the boolean equals (Object) method to objects of any combination of the classes java.lang.String, java.lang.Boolean and java.lang.Object.
* In an expression involving the operators &, |, &&, || and variables of known values state which operands are evaluated and the value of the expression.
* Determine the effect upon objects and primitive val

Section 6: Overloading, Overriding, Runtime Type and Object Orientation

* State the benefits of encapsulation in object oriented design and write code that implements tightly encapsulated classes and the relationships “is a” and “has a”.
* Write code to invoke overridden or overloaded methods and parental or overloaded constructors; and describe the effect of invoking these methods.
* Write code to construct instances of any concrete class including normal top level classes and nested classes.

Section 7: Threads

* Write code to define, instantiate and start new threads using both java.lang.Thread and java.lang.Runnable.
* Recognize conditions that might prevent a thread from executing.
* Write code using synchronized wait, notify and notifyAll to protect against concurrent access problems and to communicate between threads.
* Define the interaction among threads and object locks when executing synchronized wait, notify or notifyAll.

Section 8: Fundamental Classes in the java.lang Package

* Write code using the following methods of the java.lang.Math class: abs, ceil, floor, max, min, random, round, sin, cos, tan, sqrt.
* Describe the significance of the immutability of String objects.
* Describe the significance of wrapper classes, including making appropriate selections in the wrapper classes to suit specified behavior requirements, stating the result of executing a fragment of code that includes an instance of one of the wrapper classes, and writing code using the following methods of the wrapper classes (e.g., Integer, Double, etc.)
* doubleValue
* floatValue
* intValue
* longValue
* parseXxx
* getXxx
* toString
* toHexString