Question

I have a virtual keyboard class which implements a QWERTY alphanumeric only on-screen keyboard using JButtons in JAVA.
I have installed actionlisteners to each button so that whenever the button is clicked on the label of the button is logged.

What I want to do is that while keeping the class for keyboard separate, I want to create an instance of the keyboard class so that it receives an input and it passes it back to the main class and then that can happen in a loop. Just like how you can use has.nextLine() to keep on asking for input, I want to be able to do this by creating an instance of the on screen keyboard class.

I have already written the keyboard class and it works nicely and but the problem is that the integers are local to the keyboard class and I cant figure out a way to get it outside of the class.

Answer 1

You can use observer pattern . I am not using swing here but just to show to show it works.

Make Keyboard class Observable

    import java.util.Observable;

    public class Keybaord extends Observable {

        private String keyThatIsPressed;

        public void setKeyThatIsPressed(String keyThatIsPressed) {
            this.keyThatIsPressed = keyThatIsPressed;
            setChanged();
            notifyObservers(keyThatIsPressed);
        }

        public String getKeyThatIsPressed(){
            return keyThatIsPressed;
        }

 }

Make your main class Observer

import java.util.Observable;
import java.util.Observer;

public class MainClass implements Observer {
    private String keyThatIsPressed;

    @Override
    public void update(Observable observable,
            Object object) {
        if (object instanceof String) {
            this.keyThatIsPressed = (String) object;
            System.out.println("Key that was unlucky enough to get pressed was: "
                    + keyThatIsPressed);
        } 
    }
}