Types Of Data Members & Methods In a Class

In every java programming language , A class can containing  two types of Data Members .They are :

1.Non-static data members.
2.Static  data member.

Instance Data Member 

➢Instance data members memory space is created each every time whenever the object is created.
➢Instance data member are used for storing specific values which are suitable  for individuals.
➢Instance data member declaration should not be preceded by 'Static keyword' .
      Ex:- int a=10,20,30,40; (Instance Data Member) 
➢Datatype V 1 ,V 2,V 3........V n ;.
➢Each & every instance data member must be access with respect to Object name
     (Object . Instance Data Member Name)
➢Instance data member value are not shareable.
➢Instance data members are also called "Object level Data Members".Below following examples are the instance data type members.

 EX :  int student Id ;
       String course;
       String student name ;
       float marks;

Static Data Members 

➢ Static  data members memory space is created  once only when we defined the class then irrespective  number of times objects are created.
➢ Static date members  are used for storing  common values which are suitable for all programmers.
➢ Static data members declaration is must be preceded by "static keyboard "
➢ Static" data type V 1,V 2.......V n ;
➢ Each & every data member must be access to respect to object even with class name (obj. class).
➢ Static   data members are shareable
➢ Static data member are also called "class level data members ". Below following examples are the static data type members.

EX:  static string course ;  
         static string Delhi  ;
         static string pi ;
NOTE:-   Each every final variable must be static but a static variable  value may are  not be final .
       static final float PI= 3.14f ;
       static final String s="Java";

In Java programming a class can contain this types of methods. They are:-

1) Instance / non-static methods

2) Static methods 

 Instance method

➠Instance methods are always recommended to use to perform "Repeated Operations" such as reading the records to files & reading the records from ' Data Base ' etc. 

➠Instance methods are meant for performing specific operations which are suitable for individual programming.
➠Program-matically the definition of instance methods should not be presided by " Static keyword ".  

Ex:-  Return type  method Name ( List of       formal parameter if any)

          {

              Block of statement - Business logic

          }

➠Each of instance method must be accessed with respect to object name.

        EX:-  [Object name Instance Method name]

➠Instance methods results are not shareable because it performs specific operations.

➠Instance methods are also known as 'Object' 

Ex:-  Void callTotal( )

         {
               tot=m1+m2+m3;
         }

Static method

➠Static methods are recommended to perform one time operation such as opening a file, obtaining the data base collection.

➠Static methods are meant for performing common operation which are suitable for all programmers.

➠Static method is defined must be presided by "Static keyword". 

Ex :-  static Retype method name (list of formal parameter if any)

             {
                 Block of statements. Business logic
             }

➠Each & every static method must be access with respect to class name (even with object name). EX:- class name. static method name

➠static methods results are  shareable because their performing common operations.

➠static methods are also known as class level methods.

EX:- public static void main (String args[])

          {

                s1 .calTotal( );

                   s2 .calTotal( );

           }