Identifiers and Reserverd words in JAVA

Identifiers: A name in a program is called an identifier. It can be used for representing a class name or interface name or method name or variable names

Rules for declaring Identifiers:

Rule 1: No identifier starts with number

                  ex. int 9a;

                       int a;

Rule 2: Allowed character set

                                a to z

                               A to Z

                              0 to 9 

                             special characters  _ ,$

Rule 3: There is no restriction for length of an      identifier name

Rule 4: Predefined class names method names are allowed to use as an identifier

Rule 5: in JAVA identifiers are case sensitive

Rule 6: Reserved words are not allowed to use as identifiers

Reserved Words / keywords:

    Some identifiers are reserved words. Which are called reserved words or keywords

                 

JAVA Reserved words:

Keywords used for primitive data types

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

Keywords used for flow control

        If, else, switch, case, default, for, while, do, break, continue, return

Keywords used for exception handling

     try, catch, finally, throws, throw

Keywords used for modifiers

        public, protected, private, static, abstract, final, synchronized,  volatile, transient, native, strictfp

Keywords used for class related

        class, extends, interface, implements, package, import

Keywords used for object related

        new, instanceof, super, this

Keyword used for return type

        void

Keyword used for debugging

       assert

Keyword introduced in JDK 1.5

       enum