package strings;

public class Upper {

/** Driver Code */

public static void main(String[] args) {

String[] strings = {"ABC", "ABC123", "abcABC", "abc123ABC"};

for (String s : strings) {

assert toUpperCase(s).equals(s.toUpperCase());

}

}

/**

* Converts all of the characters in this {@code String} to upper case

*

* @param s the string to convert

* @return the {@code String}, converted to uppercase.

*/

public static String toUpperCase(String s) {

char[] values = s.toCharArray();

for (int i = 0; i < values.length; ++i) {

if (Character.isLetter(values[i]) && Character.isLowerCase(values[i])) {

values[i] = Character.toUpperCase(values[i]);

}

}

return new String(values);

}

}