How do I convert strings between uppercase and lowercase in Java?

String#toLowerCase and String#toUpperCase are the methods you need.

There are methods in the String class; toUppercase() and toLowerCase().

i.e.

String input = "Cricket!";
String upper = input.toUpperCase(); //stores "CRICKET!"
String lower = input.toLowerCase(); //stores "cricket!" 

This will clarify your doubt

Yes. There are methods on the String itself for this.

Note that the result depends on the Locale the JVM is using. Beware, locales is an art in itself.

String#toLowerCase