String method with array of integers

Please help with code. I have tried adding substring, etc, to remove the end comma. How can I do this?
Example: {1,2,3} to string is now "1,2,3,"

public static String arrayToString(int[] numbers) 
{
  String stringify = "";
  for (int index = 0; index < numbers.length; index++) 
  {
    stringify = numbers[index] + ", ";
  }
  return stringify;
}

Best way

Delete the entire method. Use Arrays.toString(int[]) instead. Why rewrite core functionality like this?

Stream way

return Arrays.stream(numbers)
  .boxed()
  .map(String::valueOf)
  .collect(Collectors.joining(", "));

StringBuilder way

StringBuilder out = new StringBuilder();
for (int i = 0; i < numbers.length; i++) {
    if (i != 0) out.append(", ");
    out.append(numbers[i]);
}
return out.toString();

Adding to a string in a loop is bad form (it wastes a ton of memory), so don't do that. The above strategies are in rough order of preference, with the top option miles ahead of the rest.

You can modify your method to the following one:

public static String arrayToString(int[] numbers) 
{
  String stringify = "";
  for (int index = 0; index < numbers.length; index++) 
  {
    stringify = numbers[index];
    if (index < numbers.length - 1) {
        stringify += ", ";
    }
  }
  return stringify;
}

I prefer to view this as having a separator before every number except for the first. Or, equally, that there's a separator before every number, but the first separator is empty.

public static String arrayToString(int[] numbers) 
{
  String separator = "";
  String stringify = "";
  for (int index = 0; index < numbers.length; index++) 
  {
    stringify += separator + numbers[index];
    separator = ", "
  }
  return stringify;
}

Note, I fixed the assignment to stringify to be += rather than =, since otherwise you're just getting the last number.

In practice, I'd probably use a StringBuilder, but I wanted to leave this as close to the original as possible. With a StringBuilder, the same separator technique can be used.