Reserved Words in java

Reserved Words in java

Reserved words:

Few words are reserved to provide some functionality or meaning,such type of reserved identifiers in java are called reserved words.

Diagram:

                                       Reserved words(53)

                                              |

                                              |

                              _  _ _  _  _  __|_ _ _ _ _ _ _ _ _

                              |                                                 |

                              |                                                 |

                          Keywords(50)                    Reserved Literals(3)

                                   |                                            |

                 _  _  _  _  _|_  _ _  __ _ _           _ _ _ _ |  __ _ __ _ _ _ _ _ 

                 |                   |                    |                          |          |             |

                 |                   |                    |                          |          |             |

           Used keywords(48)     unused keyword(2)      true     false    null

                                   |

                                   |----->goto

                                   |

                                   |----->const

Reserved words for data types: (8)

1. byte

2. short

3. int

4. float

5. double

6. char

7. 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:

In java,if a method won't return anything compulsory that method should be declared with the void return type  but it is optional in C++.

1. void

Unused keywords:

goto: It has created 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 can get compile time

error.

Reserved literals:

values for boolean data type.

1. true

2. false

3. null

Enum:

This keyword introduced in 1.5 version of java to define a group of named constants

Example:

enum Chocalate

{

Cadbury, KitKat, Eclairs, Perks;

}

Conclusions :

1. All reserved words contain only lowercase alphabet symbols in java.

2. New keywords in java are:

3. strictfp-----------1.2v

4. assert-------------1.4v

5. enum--------------1.5v

6. In java we have only new keyword but not deleted old one             because destruction of useless objects is the responsibility

 of Garbage Collection.

7. instanceof but not instanceOf

8. strictfp but not strictFp

9. const but not Constant

10. synchronized but not synchronize

11. extends but not extend

12. implements but not implement

13. import but not imports

14. int but not Int

Which of the following list contains only reserved words in java?

1.  finalize, finally,final                (invalid) //here finalize is a method                                                                        in Object class.

2.  long, Integer, short,byte          (invalid) //here Integer is a wrapper                                                                        class

3. new, delete                               (invalid) //delete is not a keyword

4. synchronized,finalize               (invalid) //finalize is a method in                                                                            Object class

5. break, return, exit, continue     (invalid) //exit is not reserved                                                                                keyword

6.  constant,goto                           (invalid) //here constant is not                                                                                reserved keyword

7. throw, throws, thrown              (invalid)//thrown is not available in                                                                        java

8. extends, imports, implements  (invalid)//imports keyword is not                                                                           available in java

9.  sizeOf,instanceof                    (invalid)//sizeOf is not reserved                                                                             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)

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