toString

Returns the joined string with prefix, delimiter-separated elements, and suffix. If no elements have been added, returns the empty value (or prefix + suffix if none was set).

Example:

    var joiner = new StringJoiner (", ", "[", "]");
    joiner.add ("x");
    joiner.add ("y");
    assert (joiner.toString () == "[x, y]");

Returns:

the joined string.