Fastest way to set all values of an array?

Question

I have a char [], and I want to set the value of every index to the same char value.
There is the obvious way to do it (iteration):

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Answer 1

I have a minor improvement on Ross Drew's answer.

For a small array, a simple loop is faster than the System.arraycopy approach, because of the overhead associated with setting up System.arraycopy. Therefore, it's better to fill the first few bytes of the array using a simple loop, and only move to System.arraycopy when the filled array has a certain size.

The optimal size of the initial loop will be JVM specific and system specific of course.

private static final int SMALL = 16;

public static void arrayFill(byte[] array, byte value) {
  int len = array.length;
  int lenB = len < SMALL ? len : SMALL;

  for (int i = 0; i < lenB; i++) {
    array[i] = value;
  }

  for (int i = SMALL; i < len; i += i) {
    System.arraycopy(array, 0, array, i, len < i + i ? len - i : i);
  }
}

Answer 2

   /**
     * Assigns the specified char value to each element of the specified array
     * of chars.
     *
     * @param a the array to be filled
     * @param val the value to be stored in all elements of the array
     */
    public static void fill(char[] a, char val) {
        for (int i = 0, len = a.length; i < len; i++)
            a[i] = val;
    }

That's the way Arrays.fill does it.

(I suppose you could drop into JNI and use memset.)