How can I return a JButton from a function and use it to do an action in a different class in java?

Question

How can I return a JButton from a function and use it to do an action in a different class, I'm creating a library just for practicing my java skills (I lack this part), and I'm trying to make it simpler for creating JFrames and JButtons by creating Objects and Functions to handle that, the problem is, on Frame.java I'm returning the JButton that was created there and then using it in with an ActionListener, but the problems are, it neither shows the error nor works, May someone provide me an explanation and, if possible, a solution?

Ctrl + F:9812934|to switch from where I return the JButton and where I use it.

Main.java

package twopackages;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


import lib.Button;
import lib.Frame;

public class Main extends Frame{
    public static void main(String[] args ){

        Frame frame = new Frame();
        Button button = new Button();

        frame.width = 400;
        frame.height = 300;
        frame.title = "title";
        frame.visible = true;

        button.width = 100;
        button.height = 30;
        button.title = "button";
        button.top = 10;
        button.left = 10;
        button.visible = true;

        frame.addButton(button);

        frame.run();

        frame.addButton(button).addActionListener(new ActionListener() {//Get JButton returned after calling function (I know it's crappy, but I could not find a way to do something similar) 9812934
            public void actionPerformed(ActionEvent arg0) {
                System.out.println("sadasdasd");
            }
        });


    }

}

Frame.java

package lib;

import javax.swing.JButton;
import javax.swing.JFrame;

import lib.Button;

public class Frame {
    public int width;
    public int height;
    public String title;
    public boolean visible;

    JFrame FRAME = new JFrame();

    public void run(){
        FRAME.setSize(width, height);
        FRAME.setTitle(title);
        FRAME.setLayout(null);
        FRAME.setLocationRelativeTo(null);
        FRAME.setVisible(visible);
        FRAME.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        FRAME.setResizable(false);
    }

    public JButton addButton(Button button){
        JButton BUTTON = new JButton();
        BUTTON.setText(button.title);
        BUTTON.setBounds(button.left, button.top, button.width, button.height);
        BUTTON.setVisible(button.visible);
        FRAME.add(BUTTON);
        return BUTTON;//Here's where I return the JButton 9812934
    }

}

Button.java

package lib;

import javax.swing.JButton;

public class Button{

    public int left;
    public int top;
    public int width;
    public int height;
    public String title;
    public boolean visible;

    JButton button = new JButton();

    public void button(){
        button.setBounds(left, top, width, height);
        button.setText(title);
        button.setVisible(visible);
    }
}

1) Java GUIs have to work on different OS', screen size, screen resolution etc. using different PLAFs in different locales. As such, they are not conducive to pixel perfect layout. Instead use layout managers, or [combinations of them](http://stackoverflow.com/a/5630271/418556) along with layout padding and borders for [white space](http://stackoverflow.com/a/17874718/418556). 2) Please learn common Java nomenclature (naming conventions - e.g. `EachWordUpperCaseClass`, `firstWordLowerCaseMethod()`, `firstWordLowerCaseAttribute` unless it is an `UPPER_CASE_CONSTANT`) and use it consistently. — Andrew Thompson, Feb 18 '16 at 13:53

score 2 · Accepted Answer · answered Feb 18 '16 at 14:35

Your code does not work since you create two instances of a JButton and add them on top of each other, which is exactly what @Andrew was warning you about in his comment. When you click the button, you are actually clicking the one that doesn't have an action listener implementation attached.

Here is the relevant bit:

//frame.addButton(button); // <-- first instance created and added

frame.run();

// ˇ second instance created and added
frame.addButton(button).addActionListener(new ActionListener() {//Get JButton returned after calling function (I know it's crappy, but I could not find a way to do something similar) 9812934
    public void actionPerformed(ActionEvent arg0) {
        System.out.println("sadasdasd");
    }
});

Simply commenting the first call fixes client code of your framework.

Trying to simplify Swing is quite a chore you've taken upon yourself. Kudos to you. There's nothing wrong with passing JButton objects around, just make sure you are passing the right one.

Note: you are calling Swing code from a thread that is not the Event Dispatch Thread. If your young framework has any hope of working properly, you'll need to fix that (wrap everything in SwingUtilities.invokeLater(Runnable)).

Oh that's totally true, I see it now, and it works, thanks for explaining and advising+1 — Kyle, Feb 18 '16 at 15:48

score 0 · Answer 2 · answered Feb 18 '16 at 13:43

0

You should add the button to the contentPane of the frame instead of the own Frame. It is always suggested to work at the level of the Panel instead of the frames in swing

answered Feb 18 '16 at 13:43

Jorge_B

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How can I return a JButton from a function and use it to do an action in a different class in java?

2 Answers2