import java.util.Random;
class bubble3
{

  static int [] randFill(int n)
  {
     Random r = new Random();
     int [] z = new int [n];
     for (int i=0;i<n;i++) z[i]=r.nextInt(n);

     return z;
   }

  static void Bubblesort(int [] a)
  {
     int N=a.length;
     for (int i=N-1;i>0;i--)
        for (int j=0;j<i;j++)
            if (a[j] > a[j+1])
           {
             int temp = a[j+1];
             a[j+1]=a[j];
             a[j]=temp;
           }

  }

  public static void main (String [] args)
  {
     for (int i=0;i<5000;i++)
       {
          int b[]=randFill(i);
	  long x=System.nanoTime();
	  Bubblesort(b);
          System.out.println(i+" "+(System.nanoTime()-x));
       }
   }
}

Do the same for mergsort