Reserved words

Reserved words:  In java some identifiers are reserved to associate some functionality or meaning such type of reserved identifiers are called reserved words.
Diagram:

Reserved words for data types:

1) byte
2) short
3) int
4) long
5) float
6) double
7) char
8) boolean
Reserved words for flow control:
1) if
2) else
3) switch
4) case
5) default
6) for
7) do 
8) while
9) break
10) continue
11) return 

Keywords for modifiers:

1) public

2) private

3) protected

4) static

5) final

6) abstract

7) synchronized

8) native

9) strictfp(1.2 version)

10) transient

11) volatile

Keywords for exception handling:

1) try

2) catch

3) finally

4) throw

5) throws

6) assert(1.4 version)

Class related keywords:

1) class

2) package

3) import

4) extends

5) implements

6) interface

Object related keywords:

1) new

2) instanceof

3) super

4) this 

Void return type keyword:

• If a method won’t return anything compulsory that method should be declared with the

void return type in java but it is optional in C++.

Unused keywords:

goto: Create several problems in old languages and hence it is banned in java.

Const: Use final instead of this.

• By mistake if we are using these keywords in our program we will get compile time

error.

Reserved literals:

1) true values for boolean data type.

2) false

3) null----------------- default value for object reference.

Enum:

• This keyword introduced in 1.5v to define a group of named constants

Example:

enum Beer

         {

                KF, RC, KO, FO;

         }

Note: All reserved words in java contain only lowercase alphabet symbols.

New keywords are:

Strictfp-----------1.2

Assert-------------1.4

Enum--------------1.5 
Which of the following list contains only java reserved words?
1) final, finally, finalize (invalid)//here finalize is a method in Object class.
2) throw, throws, thrown(invalid)//thrown is not available in java
3) break, continue, return, exit(invalid)//exit is not reserved keyword
4) goto, constant(invalid)//here constant is not reserved keyword
5) byte, short, Integer, long(invalid)//here Integer is a wrapper class
6) extends, implements, imports(invalid)//imports keyword is not available in java
7) finalize, synchronized(invalid)//finalize is a method in Object class
8) instanceof, sizeOf(invalid)//sizeOf is not reserved keyword
9) new, delete(invalid)//delete is not a keyword
10) None of the above(valid)
Which of the following are valid java keywords?
1) public(valid)
2) static(valid)
3) void(valid)
4) main(invalid)
5) String(invalid)
6) args(invalid)