为什么字符串对象未在下面的程序中更新
public class Testreturn {
public static void main(String[] args) {
ToReturn object = new ToReturn();
object.method1();
}
}
class ToReturn{
public void method1(){
String message = "message1";
updateMessage(message);
System.out.println(message);
}
private void updateMessage(String message) {
message = "Message2";
}
}