Change Variable from the inside of a ActionListener

Question

Is it possible to change a variable from inside of a ActionListener?

I mean somthing like this:

    boolean test = false;

    button.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            test = true;
        }
    });

I want to change test to true when someone presses the button.

I am totally surprised how you managed to call `addActionListener` method on a boolean `white` — Vamshi Krishna Alladi, Dec 25 '15 at 16:38
Is this JavaScript? Not Java? Please update tags in that case. — Roger Gustavsson, Dec 25 '15 at 16:40
No i mistyped it. The boolean shouldn´t be the ActionListener. I made this as an example and forget to change it. — Alexander, Dec 25 '15 at 16:43
@Roger Gustavsson, even if it was javascript one cannot call methods on a boolean value and moreover the code syntax and methods are from Java. — Vamshi Krishna Alladi, Dec 25 '15 at 16:43
Local variable vari defined in an enclosing scope must be final or effectively final. Thats the error that Eclips gets. And the first Variable gets the Error: The value of the local variable vari is not used — Alexander, Dec 25 '15 at 16:49
so `vari` is declared inside a method. Try to declare it inside a class but outside of any method. — SatyaTNV, Dec 25 '15 at 16:51
Possible duplicate of [Understanding Java's approximation to "closures"](http://stackoverflow.com/questions/14522363/understanding-javas-approximation-to-closures) — toasted_flakes, Dec 25 '15 at 17:49

score 2 · Accepted Answer · edited May 23 '17 at 12:06

I'm not sure if this helps you but if you are using a action listener I'm guessing you are working with javas swing api. In that case you are maybe extending a class like JFrame or something like that so you could use this:

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class MyFrame extends JFrame {

    private boolean booleanToChange = false;

    private JButton exampleButton;

    public MyFrame() {
        exampleButton = new JButton();
        exampleButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent actionEvent) {
                //Access a member in anonymous class
                MyFrame.this.booleanToChange = true;
            }
        });
    }
}

And here the explanation why it has to be final :) hope this helps a bit

score 0 · Answer 2 · edited Oct 20 '16 at 05:12

0

This might be what you wanted??

private boolean booly = true; 

private class WinkAction implements ActionListener
{
    public void actionPerformed(ActionEvent e) 
    {

        if (booly){
            booly = false; 
        }else {
            booly = true;
            repaint( );         
        }   
    }
}

edited Oct 20 '16 at 05:12

ArK

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answered Oct 20 '16 at 04:54

Dan Osborne

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Change Variable from the inside of a ActionListener

2 Answers2

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