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•  An identifier cannot start with a digit.

                 •  Keywords cannot be used as an identifier.
                 •  No special symbols like !, @, #, %, etc. can be used in an identifier.
                 •  Identifiers are case-sensitive, which means ‘name’ and ‘NAME’ are two different identifiers.

                 Examples of some valid identifier names are Employee123, mygood_book, _address93, FirstName,
                 age, etc.
                 Examples of some invalid identifier names are 1_Name, @Address, 1234, –Age, etc.

                 Keywords

                 Keywords are the reserved words that cannot be used as identifier names as they carry a special
                 meaning for the Java compiler. Some of the Java keywords are given below:

                                                           Java Keywords
                 abstract             class               final               interface           static
                 assert               const               float               long                switch

                 boolean              continue            for                 new                 this
                 break                default             if                  private             throw

                 byte                 do                  implements          protected           throws
                 case                 double              import              public              try
                 catch                else                instanceof          return              void
                 char                 extends             int                 short               while


                 Although reserved as a keyword in Java, const is not used and has no function.
                 There are three more reserved words in Java: true, false, and null. Technically, they are literal
                 values and not keywords. However, they cannot be used as identifiers, and they have a specific
                 meaning to the Java compiler.

                 Data Types

                 A data type is used to define the size and type of value that a variable can store. The Java
                 language  is rich  in  its data  types.  Java  provides  two  types  of  data  types:  primitive  and

                 non-primitive.
                 Primitive Data Types

                 Java provides eight basic data types, which are as given in the following table:

                  Data Type       Size (in bits)         Minimum Value                     Maximum Value
                 byte          8                   –128                            127
                 short         16                  –32768                          32767
                 int           32                  –2147483648                     2147483647
                 long          64                  –9223372036854775808            9223372036854775807
                 char          16                  0                               65535

                 float         32                  1.4E –45                        3.4028235E38


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                                                                                               Program Coding
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