method swap to the Pair class of that swaps the first and second elements value of the pair in generic Pair class in java method swap to the Pair class of that swaps the first and second elements value of the pair in generic Pair class in java method swap to the Pair class of that swaps the first and second elements value of the pair in generic Pair class in java

public class Pair

    {

       private T first;

       private T second;

   public Pair(T firstElement, T secondElement)

   {

      first = firstElement;

      second = secondElement;

   }
   public T getFirst() { return first; }
   public T getSecond() { return second; }
  public void swap()

  {
   T temp = first;

    first = second;

    second = temp;

  }
   public String toString() { return “(” + first + “, ” + second + “)”; }

}

public Pair swap() {

  return new Pair(second, first);

}

public class PairDemo

{

   public static void main(String[] args)

   {

      String[] names = { “Tom”, “Diana”, “Harry” };

      Pair result = firstContaining(names, “a”);

      System.out.println(result.getFirst());

      System.out.println(“Expected: Diana”);

      System.out.println(result.getSecond());

      System.out.println(“Expected: 1”);

      swap();

   }
   public static Pair firstContaining(

      String[] strings, String sub)

   {

      for (int i = 0; i < strings.length; i++)
      {
         if (strings[i].contains(sub))
         {
            return new Pair(strings[i], i);

         }

      }

      return new Pair(null, -1);

   }

}