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: (8) 

1. byte 
2. short 
3. int 
4. long 
5. float  
6. double 
7. char 
8. boolean

Reserved words for flow control:(11)

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:(11)

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:(6)

1. try 
2. catch 
3. finally 
4. throw 
5. throws 
6. assert(1.4 version)

Class related keywords:(6)

1. class 
2. package 
3. import 
4. extends 
5. implements 
6. interface 

Object related keywords:(4)

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++. 

1.  void

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---------values for boolean data type.
3. null-------- default value for object reference.

Enum:

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

 Example: 

enum sports

{

 bat, ball, stump;

 } 

Conclusions :

1. All reserved words in java contain only lowercase alphabet symbols.
2. New keywords in java are: 

• strictfp-----------1.2v 
• assert-------------1.4v 
• enum--------------1.5v 

1. In java we have only new keyword but not delete because destruction of useless objects is the responsibility of Garbage Collection.

• instanceof but not instanceOf
• strictfp but not strictFp 
• const but not Constant 
• syncronized but not syncronize
• extends but not extend 
• implements but not implement 
• import but not imports 
• int but not Int

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

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