Reserve Words

In java some words are reserved words to represent some meaning or functionality, such type of words are called as reserved words.

Real Example:

“Dog” is a reserve word to represent one type of animal.

“Apple” is a reserve word to represent one type of fruit.

“sleep” is a reserve word to represent one type of action.

“eat” is a reserve word to represent one type of action.

In universe , there are millions of reserved words are there that we are using in our language, but in the language java we need to remember only 53 reserved words.

Note: Total 53 reserved words are there in java

Keywords:for data type: (8)

[ byte,short,int,long,float,double,boolean,char ]

Keywords for flow Control: (11)

[ if,else,switch,case,default,do,while,for,break,continue,return ]

Keywords for Modifiers: (11)

[public,private,protected,static,final,abstract,synchronized,native,strictfp(java 1.2),transient,volatile]

Keywords for Exception Handling: (6)

[ try,catch,finally,throw,throws,assert(java 1.4) ]

Class Related Keyword: (6)

[ class,interface,extends,implements,package,import ]

Object Related Keyword: (6)

[ new,instanceof,super,this ]

Void Return Type Keyword: (1)

[ void ]

In java,return type is mandatory. If a method wo'nt return anything, then we have to declare that method with void return type, But in C langugae return type is optional and the default return type is int.

UnUsed Keywords: (2)

[ goto,const ]

goto - -> usage of goto created several problems in old languages. Hence SUN people banned this keyword in java.

const --> use of final instead of const.

Note: goto and const are unused keywords and if we are trying to use we ll get compile time error.

Reserved Word Literals: (3)

[ true,false,null ]

true,false- values for boolean data type

null- default value for object reference

enum keyword(Introduced in java 1.5): (1)

[ enum ]

We can use enum to define a group of named constants.

Example:

enum month{

JAN,FEB,MAR...DEC;

}

Conclusion:

1. All 53 reserved words in java contain only lower case alphabet symbols.
2. In java, we have only new keyword, and there is no delete keyword because destruction of useless object is the responsibility of garbage collector.
3. The following are new keywords in java.
   strictfp -->introduced in java 1.2
   assert -->introduced in java 1.4
   enum -->introduced in java 1.5
4. Some confused reserved words are like:
   strictfp but not strictFp
   instanceof but not instanceOf
   const but not constant
   synchronized but not synchronize
   import but not imports
   extends but not extend
   implements but not implement

Question 1

Which of the following list contains java reserved words?

1.new,delete

2.goto,constant

3.break,continue,return,exit,

4.fianl,finally,finalize

5.throw,throws,thrown

6.notify,notifyAll

7.implements,extends,imports

8.sizeof,instanceof

9.instanceOf,strictFp

10.byte,short,Int

11.None of the above

Question 2

Which of the following are java reserved words?

1.public

2.static

3.void

4.main

5.String

6.args