Sort a String array, whose strings represent int

Question

I have String[] array like

{"3","2","4","10","11","6","5","8","9","7"}

I want to sort it in numerical order, not in alphabetical order.

If I use

Arrays.sort(myarray);

I obtain

{"10","11","2","3","4","5","6","7","8","9"}

instead of

{"2","3","4","5","6","7","8","9","10","11"}

Answer 1

Try a custom Comparator, like this:

    Arrays.sort(myarray, new Comparator<String>() {
        @Override
        public int compare(String o1, String o2) {
            return Integer.valueOf(o1).compareTo(Integer.valueOf(o2));
        }
    });

Hope you like it!

Answer 2

I think by far the easiest and most efficient way it to convert the Strings to ints:

int[] myIntArray = new int[myarray.length];

for (int i = 0; i < myarray.length; i++) {
    myIntArray[i] = Integer.parseInt(myarray[i]);
}

And then sort the integer array. If you really need to, you can always convert back afterwards:

for (int i = 0; i < myIntArray.length; i++) {
    myarray[i] = "" + myIntArray[i];
}

An alternative method would be to use the Comparator interface to dictate exactly how elements are compared, but that would probably amount to converting each String value to an int anyway - making the above approach much more efficient.