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Thread: JButton help

  1. #1
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    Default JButton help

    hi,
    I've run into a problem with JButtons. When the applet runs the buttons are not visible until there is a mouse-over, if you resize the window the buttons disappear again until you put the mouse pointer over it.
    Has anyone run into this problem before?
    any help would be great thanks


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: JButton help

    Please post code

  3. #3
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    Default Re: JButton help

    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import java.applet.*;
     
    public class JButtonTest extends JApplet implements ActionListener
    {
    	JButton btn1, btn2, btn3;
    	Container pane;
    	public void init()
    	{
    		pane = getContentPane();
    		pane.setLayout(new FlowLayout());
    		btn1 = new JButton("button 1");
    		btn2 = new JButton("button 2");
    		btn3 = new JButton("button 3");
    		pane.add(btn1);
    		pane.add(btn2);
    		pane.add(btn3);
    	}
    	public void paint(Graphics g)
    	{
    		g.drawString("hello", 10, 10);
    	}
    	public void actionPerformed(ActionEvent e)
    	{
     
    	}
    }

  4. #4
    Super Moderator helloworld922's Avatar
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    Default Re: JButton help

    Ok, from what I understand about how Swing/Applets paint their sub-components is via the paint method. Since you over-wrote the paint method, the code for telling these components to paint themselves isn't there. I'm not quite sure why the components get painted after you put your mouse over them, though.

    There are two solutions:
    1. Call the super paint method inside your paint method.

    public void paint(Graphics g)
    {
         super.paint(g);
         // rest of your paint code
    }

    Note that if you do this, it will have the default panel background color as opposed to the white one. You can change this by using the setBackground() method.

    this.setBackground(Color.white);

    2. Manually calling the update method for the buttons. You can even create a loop using the getComponentCount() and getComponent() methods to make sure you re-painted all the components inside your panel, even if you decide to add more components later.

    public void paint(Graphics g)
    {
         for (int i = 0; i < this.getComponentCount(); i++)
         {
              this.getComponent(i).repaint();
         }
    }

  5. The Following User Says Thank You to helloworld922 For This Useful Post:

    tabutcher (March 9th, 2010)

  6. #5
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    Default Re: JButton help

    thanks you helloworld922

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