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P. 229

Let us take the following example:

                                   class calculate
                                   {
                                              int a, b, s;
                                              void accept (int m, int n)  // Formal Parameters
                                              {
                                                    a=m; b=n;
                                              }
                                              void sum ()
                                              {
                                                    s=a + b;
                                                    System.out.println("The result is:" +s);
                                              }
                                              public static void main ()
                                              {
                                                    calculate ob= new calculate ();
                                                    int i=4, j=2;
                                                    ob.accept(i, j);            // Actual Parameters
                                                    ob.sum();
                                              }
                                   }

                 In the above example, i and j are actual parameters that contain 4 and 2 as values, whereas the formal parameters m
                 and n receive the values in the order of 4 and 2, and the methods do the task of addition.


                     10.6 INVOKING A METHOD
                 After declaring and defining a method, we have to call it or invoke it so that the task assigned to the method can be
                 executed. Let us take an example:


                           class method
                           {
                             public static void main ()
                            {                                                void sum (int i, int j)
                              int a=8, b=4;                                  {
                               method obj = new method();                       System.out.println(i + j);
                              obj.sum (a, b);                                }
                              obj.diff (a, b);
                              a=5; b=6;
                                                                             void diff (int i, int j)
                              obj.sum (a, b);
                                                                             {
                              a=10; b=20;
                                                                                System.out.println(i - j);
                              obj.sum (a, b);
                                                                             }
                             }
                           }
                 Explanation:
                 1.  The sum( ) method is called for three times:
                         st
                    a.  1  time with values 8 and 4, and will print 12
                    b.  2  time with values 5 and 6, and will print 11
                         nd
                         rd
                    c.  3  time with values 10 and 20, and will print 30
                 2.  The diff( ) method will be executed once and will calculate the difference between 8 and 4, and will print 4;
                 There are two ways to invoke a method, which are Pass by Value and Pass by Reference. Let us study them in detail.

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