Combine and sort two arrays of different length in Java

Question

I am looking for a solution for my 'problem', that isn't an ugly hack.

In my Java code I have two arrays, both of an unknown length (so they will probably be of different length). I would like to sort them like this:

Array A: {1, 2, 3, 4, 5}
Array B: {6, 7, 8}

New Array: {1, 6, 2, 7, 3, 8, 4, 5}

Is there a nice way to accomplish this?

Thanks

Answer 1

int[] res = new int[a.length + b.length];
int p = 0;
int last = Math.max(a.length, b.length);
for (int i = 0 ; i != last ; i++) {
    if (i < a.length) res[p++] = a[i];
    if (i < b.length) res[p++] = b[i];
}

Answer 2

If it is likely that there are many more in one array than the other, it should be faster to zip the first part and then bulk copy the rest using System.arrayCopy. It also simplifies dasblinkenlight's for loop by removing the ifs.

int[] res = new int[a.length + b.length];
int p = 0;
//zip what we can
int last = Math.min(a.length, b.length);    
for (int i = 0; i != last; i++) {
    res[p++] = a[i];
    res[p++] = b[i];
}
//now add the remaining
int aRemain = a.length - last;
if(aRemain > 0) {
  System.arrayCopy(a, last, res, p, aRemain);
}
else
{
  int bRemain = b.length - last;
  if(bRemain > 0) {
    System.arrayCopy(b, last, res, p, bRemain);
  }
}