How to swap two numbers in java

Question

i have an idea in c but i don't know in java..somenoe like to share their idea i appreciate a lot...
here is a sample code in c...hope u can help me in java.....thanks a lot ....
#include<stdio.h>
void swap(int x, int y)
int temp;
temp=x;
x=y;
y=temp;
  void main(void)
    int x=10,y=20;
      clrscr();
printf("Before swap:x=%d,y-%d", x,y);
    swap(x,y);
printf("\n After swap:x=%d,y=%d",x,y);
   getch();
#include<stdio.h>
void swap(int* x, int* y)
int temp;
temp=*x;
*x=*y;
*y=temp;
void main(void)
int x=10,y=20;
clrscr();
printf("Before swap:x=%d,y-%d", x,y);
swap(&x,&y);
printf("\n After swap:x=%d,y=%d",x,y);
getch();
}My aim of this program is to make one java file and 2 class files in java and display the output . The first output would be the number before swapping and the number after swapping.....

Answer 1

There are several ways to achieve the results. You can use an array or a custom "Swaper" class to swap two values. Here is an example using generics for better code reuse.
public class Swapper<T> {
   private T first;
   private T second;
   public Swapper(T first, T second) {
      this.first = first;
      this.second = second;
   public void swap() {
      T temp = first;
      first = second;
      second = temp;
   public <T> Swapper<T> swap(T first, T second) {
      return new Swapper<T>(second, first);
   public T getFirst() {return first;}
   public T getSecond() {return second;}
   private static void swap(int[] num) {
      if (num.length != 2) {
         throw new IllegalArgumentException("num array must be of length 2");
      int temp = num[0];
      num[0] = num[1];
      num[1] = temp;
   public static void main(String[] args) {
      // method 1: use array
      int[] num = {1, 2};
      System.out.printf("Before swap:first=%d,second=%d\n", num[0], num[1]);
      Swapper.swap(num);
      System.out.printf("After swap:first=%d,second=%d\n", num[0], num[1]);
      // method 2: use a custom "Swapper" class
      Swapper<Integer> swapper = new Swapper<Integer>(3, 4);
      System.out.printf("Before swap:first=%d,second=%d\n", swapper.getFirst(), swapper.getSecond());
      swapper.swap();
      System.out.printf("After swap:first=%d,second=%d\n", swapper.getFirst(), swapper.getSecond());
      // method 2: using another data type
      Swapper<String> stringSwapper = new Swapper<String>("C#", "Java");
      System.out.printf("Before swap:first=%s,second=%s\n", stringSwapper.getFirst(), stringSwapper.getSecond());
      stringSwapper.swap();
      System.out.printf("After swap:first=%s,second=%s\n", stringSwapper.getFirst(), stringSwapper.getSecond());
      /*    --- OUTPUT ---
       * Before swap:first=1,second=2
       * After swap:first=2,second=1
       * Before swap:first=3,second=4
       * After swap:first=4,second=3
       * Before swap:first=C#,second=Java
       * After swap:first=Java,second=C#
}