Java Swing：访问另一个类的面板组件

Question

Hi i basically have two classes, one main and one just to separate the panels, just for code readability really.

i have :

public class Main{

   public static void main (String args[]) {
    JFrame mainJFrame;
    mainJFrame = new JFrame();

    //some other code here

    CenterPanel centerPanel = new CenterPanel();
    centerPanel.renderPanel();
    mainFrame.add(centerPanel.getGUI());

   }


}

class CenterPanel{
    JPanel center = new JPanel();

    public void renderPanel(){
        JButton enterButton = new JButton("enter");
        JButton exitButton = new JButton("exit");
        center.add(exitButton);
        center.add(enterButton);
    }

    public JComponent getGUI(){
        return center;
    }
}

Above code works perfectly. It renders the centerPanel which contains the buttons enter and exit. My question is:

I still need to manipulate the buttons in the main, like change color, add some action listener and the likes. But i cannot access them anymore in the main because technically they are from a different class, and therefore in the main, centerPanel is another object.

How do I access the buttons and use it (sets, actionlisteners, etc)? even if they came from another class and i still wish to use it inside the main?Many Thanks!

Answer 1

Make the buttons members of CenterPanel

class CenterPanel{
    JPanel center = new JPanel();

    JButton enterButton;
    JButton exitButton;

    public void renderPanel(){
        enterButton = new JButton("enter");
        exitButton = new JButton("exit");
        center.add(exitButton);
        center.add(enterButton);
    }

    public JButton getEnterButton()
    {
       return enterButton;
    }

    public JButton getExitButton()
    {
       return exitButton;
    }

    public JComponent getGUI(){
        return center;
    }
}

Answer 2

You have reference to centerPanel in your main method. After you invoke centerPanel.renderPanel(); the buttons will be added to the 'center' reference of type JPanel in CenterPanel instance. You can get the reference of 'center' by invoking centerPanel.getGUI(); in main method.This will return the center reference of type JComponent . JComponent is a awt container.so, you can call center.getComponents() . This will return all the components in an array present in the JPanel. ie center reference. You can iterate them, get their type and do whatever you want.