toLowerCase

toLowerCase()
toLowerCase(locale);

returns the String, converted to lowerspace.

package lang;
 
public class Lang {
 
    public static void main(String[] args) {
 
        String str = "TEST 1234";
 
        str = str.toLowerCase();
        // str = str.toLowerCase(Locale.SIMPLIFIED_CHINESE); // for Simplified Chinese
 
        System.out.println(str+" in lowercase");
    }
}

 test 1234 in lowercase