public boolean either24(int[] nums) {
  boolean got2 = false;
  boolean got4 = false;
  for (int i = 0; i < nums.length-1; i++) {
    int n1 = nums[i];
    int n2 = nums[i+1];
    if (n1 == n2) {
      if (n1 == 2) {
        got2 = true;
      }
      else if (n2 == 4) {
        got4 = true;
      }
    }
  }
  return got2 != got4;
}

public boolean either24(int[] nums) {
  boolean got2 = false;
  boolean got4 = false;
  for (int i = 0; i < nums.length-1; i++) {
    int n1 = nums[i];
    int n2 = nums[i+1];
    if (n1 == n2 && n1 == 2) {
      got2 = true;
    }
    else if (n1 == n2 && n1 == 4) {
      got4 = true;
    }
  }
  return got2 != got4;
}