code: public static void swap(long[] longArray1, int array1Index, long[] longArray2, int array2Index) {
          if(longArray1[array1Index] != longArray2[array2Index]) {
              long hold = longArray1[array1Index];
              longArray1[array1Index] = longArray2[array2Index];
              longArray2[array2Index] = hold;
          }
          
      }
docs: Swap the elements of two long arrays at the specified positions.
  
  @param longArray1 one of the arrays that will have one of its values swapped.
  @param array1Index the index of the first array that will be swapped.
  @param longArray2 the other array that will have one of its values swapped.
  @param array2Index the index of the second array that will be swapped.