Question

I have a method called getTheUserInput in a class which returns a String which updates based on user actions, which is located inside a class called Board.java. I have action which adds data to a String which I know works.

In my other class I have a JLabel which has been set to equal the returned String of the method, as follows:

JLabel l = new JLabel(b.getTheUserInput());

However, when I run the application no matter what input the user provides, the string updates, but the JLabel stays blank. How do I keep the JLabel updated consistently with the string in the other class?

Answer 1

You’d …. need to update the JLabel.

myJLabel.setText(newString);

Strings in Java are immutable so they can never change / be changed.

For example when you say, “I have action which adds data to a String which I know works.” … you’re incorrect. You’ve created a new String. You need to supply the JLabel with the new String (the user’s input) if you want to change the text.

Edit: To answer the last part of your question; you’d need to keep track of the JLabel and update it as I show above every time the user provides input (in the event handler for whatever that is). Using the Observer Pattern might be an option as Java provides it via Observer and Observable