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Note: In pass  by reference,  any change in  the formal parameter  will  also  reflect on  the actual
                       parameter. Also, only non-primitive data can be used in pass by reference.


                 10.6.3 Difference Between Pass by Value and Pass by Reference
                                     Pass by Value                                     Pass by Reference
                 The copy of the actual parameters is sent to the formal  The actual parameters and the formal parameters share
                 parameter.                                           the same location in the memory.
                 Any change in the formal parameter will not reflect on  Any change in the formal parameter while the method is
                 the actual parameter.                                executing, the actual parameter is also changed.
                 Only primitive data can be used.                     Only non-primitive data can be used.


                     10.7 THE STATIC AND NON-STATIC METHODS
                 If the word static is used before any method, then it means that the method directly belongs to the class and not to
                 its instance. This means that only one copy of the method is created, which is used throughout the program. Java
                 supports both static and non-static methods.
                 A static method is common to all the objects in the class. It can be called by its class name also. The word static is
                 written before the method name. For example,

                    public static void display()
                    {
                        System.out.println("This is static method");
                    }
                 A non-static method is also known as instance method. The word static in not written before the method name. For
                 example,
                    public void display()
                    {
                        System.out.println("This is non-static method");
                    }
                 Let us take the following example:
                   1  class calculator

                   2  {   public void sum(int a, int b)
                   3      {   int c= a + b;

                   4          System.out.println("Sum of the numbers : "+c);

                   5      }
                   6      public static void difference (int a, int b)
                   7      {   int d= a - b;





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