Swing Panels Color Change

Question

I am trying to launch multiple JFrames with a custom panel that I created called subpanel. [In case you are wondering about the naming, I have another class called masterpanel, which contains a button that launches a new frame containing a new instance of subpanel.

The purpose of the subpanel is that when the user hits the enter button, the color changes. Currently, I have each subpanel contain an inner class called EnterAction, which calls setBackground to change the color.

I was wondering how I can modify this so that I can synchronize the color change between all of my subpanels.

Currently, I have a variable green, which I believe I can pass between all of my panels. However, I'm not sure how I can get the EnterAction to change all of the currently active panels?

I was thinking of creating a list of active subpanels? But will this cause an additional problem that I would need to maintain the list if the user closes a subpanel?

Here is my code:

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.KeyStroke;

public class SubPanel extends javax.swing.JPanel
{   
    private Action enterAction;

    public SubPanel() 
    {
        initComponents();
        enterAction = new EnterAction();

            //KeyBindings on the enter button
        this.getInputMap().put(KeyStroke.getKeyStroke( "ENTER" ), "doEnterAction");
        this.getActionMap().put( "doEnterAction", enterAction );
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        setForeground(new java.awt.Color(1, 1, 1));
        setToolTipText("");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    // End of variables declaration                   

    private static int green = 240;

    private class EnterAction extends AbstractAction 
    {   
        @Override
        public void actionPerformed(ActionEvent ae) 
        {
            //System.out.println("Enter button is pressed");
            green -= 5;
            if (green <= 0) green = 0;
            setBackground(new java.awt.Color(255, green, 255));
        }
    }
}

EDIT: There's going to be a maximum of 5 panels. This eliminates the need to create a list maintain active panels.

*"I am trying to launch multiple JFrames"* See [The Use of Multiple JFrames, Good/Bad Practice?](http://stackoverflow.com/a/9554657/418556) — Andrew Thompson, May 05 '13 at 16:01
+1 for [`Action`](http://docs.oracle.com/javase/tutorial/uiswing/misc/action.html). — trashgod, May 05 '13 at 16:16
@AndrewThompson I am creating a model for something. I guess I can change the scope of my application. There's going to be a maximum of 5 windows that can be opened. — Rhs, May 05 '13 at 16:47

score 2 · Accepted Answer · edited May 23 '17 at 10:32

2

Instead, create a PanelColorModel that holds the current color. Let interested panels register as a listener to this model, using one of the observer pattern implementations suggested here. Then your Action can update the model and listeners can react accordingly.

edited May 23 '17 at 10:32

Community

1
1

answered May 05 '13 at 16:15

trashgod

203,806
29
246
1,045

score 0 · Answer 2 · answered May 05 '13 at 17:27

0

You can try to define a static Color attribute, so every time you hit Enter every subpanel will have the same color. Something like:

static Color subpanelBackgroundColor; //Every instance will have this.

answered May 05 '13 at 17:27

Julián Chamalé

607
11
23

1

I don't think this is accurate. Even if all panels share a static `color` variable, there still needs to exist an event that calls setBackground for each panel. – Rhs May 06 '13 at 13:49

Swing Panels Color Change

2 Answers2