call by value and call y refrence in java

1/*call by refrence doesnot change the value of parameters(a and b ) in
2main function but where as passing the values by refrence changes the values 
3of and b in the main function
4*/
5//CALL BY REFERENCE
6public class JavaTester {
7   public static void main(String[] args) {
8      IntWrapper a = new IntWrapper(30);
9      IntWrapper b = new IntWrapper(45);
10      System.out.println("Before swapping, a = " + a.a + " and b = " + b.a);
11      // Invoke the swap method
12      swapFunction(a, b);
13      System.out.println("\n**Now, Before and After swapping values will be different here**:");
14      System.out.println("After swapping, a = " + a.a + " and b is " + b.a);
15   }
16   public static void swapFunction(IntWrapper a, IntWrapper b) {
17      System.out.println("Before swapping(Inside), a = " + a.a + " b = " + b.a);
18      // Swap n1 with n2
19      IntWrapper c = new IntWrapper(a.a);
20      a.a = b.a;
21      b.a = c.a;
22      System.out.println("After swapping(Inside), a = " + a.a + " b = " + b.a);
23   }
24}
25class IntWrapper {
26   public int a;
27   public IntWrapper(int a){ this.a = a;}
28}
29/*
30------------------------------------OUTPUT--------------------------------------
31Before swapping, a = 30 and b = 45
32Before swapping(Inside), a = 30 b = 45
33After swapping(Inside), a = 45 b = 30
34**Now, Before and After swapping values will be different here**:
35After swapping, a = 45 and b is 30
36--------------------------------------------------------------------------------
37*/
38//CALL BY VALUE
39public class Tester{
40   public static void main(String[] args){
41      int a = 30;
42      int b = 45;
43      System.out.println("Before swapping, a = " + a + " and b = " + b);
44      // Invoke the swap method
45      swapFunction(a, b);
46      System.out.println("\n**Now, Before and After swapping values will be same here**:");
47      System.out.println("After swapping, a = " + a + " and b is " + b);
48   }
49   public static void swapFunction(int a, int b) {
50      System.out.println("Before swapping(Inside), a = " + a + " b = " + b);
51      // Swap n1 with n2
52      int c = a;
53      a = b;
54      b = c;
55      System.out.println("After swapping(Inside), a = " + a + " b = " + b);
56   }
57}
58/*
59-----------------------------------OUTPUT---------------------------------------
60Before swapping, a = 30 and b = 45
61Before swapping(Inside), a = 30 b = 45
62After swapping(Inside), a = 45 b = 30
63**Now, Before and After swapping values will be same here**:
64After swapping, a = 30 and b is 45
65--------------------------------------------------------------------------------
66*/
67
68
69
70
71
72