Merge two sorted arrays in a single array with space

Problem

A sorted array has M elements and N blank spaces. Another array has N sorted elements. merge this two arrays in the first array of size M+N

Solution

Start filling the array from back side. That is from the blank positions of first array. As the space is equal to the second array size, it will never overwrite the first array's original values.

Code

public class MergeInSingleArray
{
 public static void main(String[] args)
 {
  int M = 10;
  int N = 12;
  int[] array1 = new int[M + N];
  int[] array2 = new int[N];
  fillElementsSorted(array1, M);
  fillElementsSorted(array2, N);
  printArray(array1);
  printArray(array2);
  merge(array1, array2, M, N);
  printArray(array1);
 }

 private static void printArray(int[] array)
 {
  for (int i : array)
   System.out.print(i + ",");
  System.out.println();

 }

 private static void merge(int[] array1, int[] array2, int M, int N)
 {
  int index = M + N - 1;
  int i = M - 1;
  int j = N - 1;
  while (true)
  {
   if (array1[i] > array2[j])
    array1[index--] = array1[i--];
   else
    array1[index--] = array2[j--];
   if (j < 0)
    break;
   if (i < 0)
   {
    while (index >= 0)
    {
     array1[index] = array2[index];
     index--;
    }
    break;
   }
  }
 }

 private static void fillElementsSorted(int[] array1, int fillCount)
 {
  array1[0] = (int) (Math.random() * 5);
  for (int i = 1; i < fillCount; ++i)
  {
   array1[i] = array1[i - 1] + (int) (Math.random() * 5);
  }
 }

}