package Strings; public class Lower { /** Driver Code */ public static void main(String[] args) { String[] strings = {"ABC", "ABC123", "abcABC", "abc123ABC"}; for (String s : strings) { assert toLowerCase(s).equals(s.toLowerCase()); } } /** * Converts all of the characters in this {@code String} to lower case * * @param s the string to convert * @return the {@code String}, converted to lowercase. */ public static String toLowerCase(String s) { char[] values = s.toCharArray(); for (int i = 0; i < values.length; ++i) { if (Character.isLetter(values[i]) && Character.isUpperCase(values[i])) { values[i] = Character.toLowerCase(values[i]); } } return new String(values); } }