### Question:
SimpleStringUtils { public static void replaceNonWordChars(StringValue string, char replacement) { final char[] chars = string.getCharArray(); final int len = string.length(); for (int i = 0; i < len; i++) { final char c = chars[i]; if (!(Character.isLetter(c) || Character.isDigit(c) || c == '_')) { chars[i] = replacement; } } } private  SimpleStringUtils(); static void toLowerCase(StringValue string); static void replaceNonWordChars(StringValue string, char replacement);  }### Answer:
@Test public void testReplaceNonWordChars() { StringValue testString = new StringValue("TEST123_@"); SimpleStringUtils.replaceNonWordChars(testString, '!'); assertEquals(new StringValue("TEST123_!"), testString); }