### Question:
StringUtils { public static String replaceAnyOf(String value, String chars, char replacement) { char[] tmp = new char[value.length()]; int pos = 0; for (int ix = 0; ix < tmp.length; ix++) { char ch = value.charAt(ix); if (chars.indexOf(ch) != -1) tmp[pos++] = replacement; else tmp[pos++] = ch; } return new String(tmp, 0, tmp.length); }  static String replaceAnyOf(String value, String chars,
                                    char replacement); static String normalizeWS(String value); static String[] split(String str); static String join(String[] pieces);  }### Answer:
@Test public void testEmptyReplace() { assertEquals("", StringUtils.replaceAnyOf("", "abc", ' ')); }
@Test public void testNoReplacements() { assertEquals("123", StringUtils.replaceAnyOf("123", "abc", ' ')); }
@Test public void testAllReplacements() { assertEquals(" ", StringUtils.replaceAnyOf("abc", "abc", ' ')); }