清华大学：JAVA教学课件：4-5

public class StringTest {
public static void main(String args[]) {
String s = "This is a test String!";
System.out.println("before changed,s= " + s);

String t = s.toLowerCase();
System.out.println("after changed,s= " + s);
System.out.println("t= " + t);
}
}