public int[] evenOdd(int[] nums) {
  int[] a = new int[nums.length];
  int j = 0;
  for (int n : nums) {
    if (n % 2 == 0) {
      a[j] = n;
      j++;
    }
  }
  for (int n : nums) {
    if (n % 2 == 1) {
      a[j] = n;
      j++;
    }
  }
  return a;
}