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Thread: How can I place a pause between repaints when handling a button event?

  1. #1
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    Question How can I place a pause between repaints when handling a button event?

    I am new to this forum and Java, so this is my first post.

    I have some gray JButtons and, when clicked, I want them to turn red for 500 milliseconds and then blue. I put an action listener on them and handled the event with Thread.sleep(500) between filling red and filling blue, and even a repaint() between those (to the panel where the buttons are displayed), but apparently the thread that does the repaints is postponed until after the thread that sleeps. It seems like there should be a simple solution, but I cannot think of one. What I have tried is this (and it just draws the buttons pressed as blue):

    [code = Java]
    private boolean handleControl(JButton buttonPressed)
    {
    buttonPressed.setBackground(Color.RED);
    gui.repaint();
    try
    {
    Thread.sleep(500);
    }
    catch(InterruptedException e)
    {
    }
    buttonPressed.setBackground(Color.BLUE);

    return true;
    }
    [/code]

    My question is, can this be done in a simple way, or do I have to create my own thread and put everything on it?


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    Default Re: How can I place a pause between repaints when handling a button event?

    No, don't sleep the thread in a Swing application. Use a javax.swing.Timer to do most kinds of animation, including changing component colors.

    The 'Java' in your code tags should not be capitalized. Make sure I'm right, and edit that.

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    Default Re: How can I place a pause between repaints when handling a button event?

    Quote Originally Posted by GregBrannon View Post
    No, don't sleep the thread in a Swing application. Use a javax.swing.Timer to do most kinds of animation, including changing component colors.

    The 'Java' in your code tags should not be capitalized. Make sure I'm right, and edit that.
    Thanks, Greg! Here's a sample I was able to code that solves my problem using a Swing Timer as you suggested:

    [code = java]
    // *************** my EventHanlder *******************
    // * *
    // * Sets button color to red for specified time *
    // * then changes color to blue *
    // * *
    // * Morris Night *
    // ************************************************** *

    import javax.swing.*;
    import java.awt.Color;
    import java.awt.event.*;

    public class EventHandler implements ActionListener
    {
    private JButton buttonPressed;
    private Timer t;

    public EventHandler(Timer tt)
    {
    t = tt;
    }

    public void actionPerformed(ActionEvent e)
    {
    Object whatHappened = e.getSource();

    if ( whatHappened instanceof javax.swing.Timer)
    {
    buttonPressed.setBackground(Color.BLUE);
    return;
    }

    if ( whatHappened instanceof javax.swing.JButton)
    {
    buttonPressed = (JButton)whatHappened;
    buttonPressed.setBackground(Color.RED);
    t.start();
    return;
    }

    }
    }

    // ********* Application using EventHandler *****************
    // *** This version sets the pause to 1 second *************

    import javax.swing.*;
    import java.awt.*;

    public class ColoredButtons extends JFrame
    {
    JButton button1;
    JButton button2;
    EventHandler eventHandler;
    Timer t;

    public ColoredButtons()
    {
    setSize(100,100);
    setDefaultCloseOperation(EXIT_ON_CLOSE);

    button1 = new JButton("one");
    button2 = new JButton("two");
    button1.setBackground(Color.GRAY);
    button2.setBackground(Color.GRAY);

    t = new Timer(1000, null); // ** pause set to 1 second **
    t.setRepeats(false);
    eventHandler = new EventHandler(t);

    t.addActionListener(eventHandler);
    button1.addActionListener(eventHandler);
    button2.addActionListener(eventHandler);

    getContentPane().add(button1,BorderLayout.WEST);
    getContentPane().add(button2,BorderLayout.EAST);
    }

    public static void main(String args[])
    {
    ColoredButtons coloredButtons = new ColoredButtons();
    coloredButtons.setVisible(true);
    }
    }
    [/code]

    --- Update ---

    By the way, the reason for this detail can be seen in an Applet I am polishing up.
    It can be viewed via this link: Navajo Lesson
    -- Morris --

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    Default Re: How can I place a pause between repaints when handling a button event?

    And maybe no spaces (in code tags). I only know how to do them right, so I'm always surprised at the number of ways they can be done wrong.

    Glad that you got it working and are learning something in the process.

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