Java Arrays::toString(Object[] v)の進化

今日はインタネットでjava.util.Arraysのソースを参考しました、 ２００７年くらいGNU Classpathのソースで、その時OpenJDKまだ誕生されません。 その中でtoString(Object[] v)の実装は以下です。

/**
 * Returns a String representation of the argument array.  Returns "null"
 * if <code>a</code> is null.
 * @param v the array to represent
 * @return a String representing this array
 * @since 1.5
 */
public static String toString(Object[] v)
{
  if (v == null)
    return "null";
  StringBuilder b = new StringBuilder("[");
  for (int i = 0; i < v.length; ++i)
    {
      if (i > 0)
        b.append(", ");
      b.append(v[i]);
    }
  b.append("]");
  return b.toString();
}

OpenJDK 25のソースも参考して、同じメソッドだけれど以下ように実装されます。

/**
 * Returns a string representation of the contents of the specified array.
 * If the array contains other arrays as elements, they are converted to
 * strings by the {@link Object#toString} method inherited from
 * {@code Object}, which describes their <i>identities</i> rather than
 * their contents.
 *
 * <p>The value returned by this method is equal to the value that would
 * be returned by {@code Arrays.asList(a).toString()}, unless {@code a}
 * is {@code null}, in which case {@code "null"} is returned.
 *
 * @param a the array whose string representation to return
 * @return a string representation of {@code a}
 * @see #deepToString(Object[])
 * @since 1.5
 */
public static String toString(Object[] a) {
    if (a == null)
        return "null";

    int iMax = a.length - 1;
    if (iMax == -1)
        return "[]";

    StringBuilder b = new StringBuilder();
    b.append('[');
    for (int i = 0; ; i++) {
        b.append(String.valueOf(a[i]));
        if (i == iMax)
            return b.append(']').toString();
        b.append(", ");
    }
}

どちらも素晴らしいが、GUNのほうが分かりやすいと個人的に思います。