public class Swaps { //Java classes should begin with a capital letter, just about everything else with a small letter.
  public static void main(String[] arg){
    int[] arr = {10, 20};
    Swaps.swap(arr); //I made the method static, so there is no need to create an instance of Swaps
    System.out.println("a="+arr[0]+"b="+arr[b]);
  }
  public static void swap(int[] arr) {
    int t = arr[0];
    arr[0] = arr[1];
    arr[1] = t;
  }
}

public class Util
{
   public static int[] swap(int a, int b)
   {
      int[] swappedValues = new int[2];
      int[0] = b;
      int[1] = a;
      return swappedValues;
   }
}

int[] arr = {10,20};
//(pos1)
arr = swappedValues(arr);

public class Swap
{
    public static void main(String[] args)
    {
        Swap s = new Swap();
        Point p = new Point(25, 40);
 
        System.out.println("x = " + p.getX() + ", y = " + p.getY());
 
        s.swap(p);
 
        System.out.println("x = " + p.getX() + ", y = " + p.getY());
    }
 
    public void swap(Point p)
    {
        int temp;
 
        temp = p.getX();
        p.setX(p.getY());
        p.setY(temp);
    }
}
 
public class Point
{
    private int x;
    private int y;
 
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
 
    public void setX(int x) {
        this.x = x;
    }
 
    public void setY(int y) {
        this.y = y;
    }
 
    public int getX() {
        return this.x;
    }
 
    public int getY() {
        return this.y;
    }
}

public class Swap2
{
    int x;
    int y;
 
    public static void main(String[] args)
    {
        Swap2 s = new Swap2();
 
        s.x = 25;
        s.y = 40;
 
        System.out.println("x = " + s.x + ", y = " + s.y);
 
        s.swap();
 
        System.out.println("x = " + s.x + ", y = " + s.y);
    }
 
    public void swap()
    {
        int temp;
 
        temp = x;
        x = y;
        y = temp;
    }
}

static void swap( int [] array, int index1, int index2 )
{
   int temp = array[index1];
   array[index1] = array[index2];
   array[index2] = temp;
}