在切换按钮上将JPanel添加到其他Jpanel上单击 [英] JPanel is added onto other Jpanel on togglebutton Click

问题描述

我正在尝试制作一个弹出面板，该面板在JToggleButton的帮助下被激活. 我希望在选择ToggleButton时将JPanel添加到另一个Jpanel上，而在取消选择ToggleButton时将其隐藏.

I am trying to make a popup panel which is activated with the help of JToggleButton. I want the JPanel to be added onto the other Jpanel when ToggleButton is selected and hides when the ToggleButton is deselected.

我已经声明了JToggleButton并使用了ItemListener.但是发生的是，当我选择ToggleButton时，如果我取消选择并再次选择它，则会创建一个面板，然后再次添加另一个JPanel，依此类推，然后单击5次，则什么也不会出现.

I have declared the JToggleButton and used ItemListener. But What is happening is when i select the ToggleButton a panel is created if i deselect and Select it again another JPanel is added again and so on and After 5 clicks , Nothing appears.

public static JPanel createDesignButtons(){
    designButtonsPanel.setOpaque(false);
    BoxLayout boxLayout = new BoxLayout(designButtonsPanel, BoxLayout.LINE_AXIS);
    designButtonsPanel.setLayout(boxLayout);

    mainButton.setIcon(Icons.venueIcon);
    mainButton.setBorderPainted(false);
    mainButton.setPreferredSize(new Dimension(40,40));
    mainButton.addItemListener(new ItemListener() {
    public void itemStateChanged(ItemEvent ev) {
        if(ev.getStateChange()==ItemEvent.SELECTED){
        designButtonsPanel.add(createButtonsDialog());
        designButtonsPanel.validate();
        } else if(ev.getStateChange()==ItemEvent.DESELECTED){
        System.out.println("button is not selected");
        }
    }
});
    designButtonsPanel.add(mainButton);

    JLabel padding = new JLabel(" ");
    padding.setPreferredSize(null);

    JLabel divider = new JLabel("", Icons.dividerIcon, JLabel.CENTER);
    divider.setPreferredSize(new Dimension(3,45));
    designButtonsPanel.add(divider);


    SwingUtilities.updateComponentTreeUI(designButtonsPanel);
    return(designButtonsPanel);
}

上面的代码显示了mainButton是要对其进行操作的切换按钮，而DesignButtonPanel是作为父项的Panel.

The above code is showing the mainButton is togglebutton that i want action on and the DesignButtonPanel is the Panel which is parent.

public static JPanel createButtonsDialog(){

    JPanel buttonsPanel = new JPanel();
    buttonsPanel.setBorder(new LineBorder(Color.gray,1));
    return buttonsPanel;
}

此类显示我要添加到父面板的面板

This class show the panel i would like to add onto parent panel

当JtoggleButton被选中时，如何才能仅添加面板一次，而取消选中该面板时又如何隐藏呢?

How can i get the Panel added only once when the JtoggleButton is Selected and hides when its Deselected?

推荐答案

问题是您一直在创建JPanel的实例. 如果未选择JToggleButton，则可以remove JPanel；如果选择了按钮，则可以添加已经创建的JPanel实例. 看这个简单的例子:

The problem is you keep creating instances of your JPanel. You could remove the JPanel if your JToggleButton is not selected and add an already created instance of your JPanel if the button is selected. See this simple example:

public class MainFrame extends JFrame {

private JPanel topPanel = new JPanel();
private JPanel centerPanel = new JPanel();
private JToggleButton toggleButton = new JToggleButton("Toggle");

public MainFrame() {
    this.setVisible(true);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);
    this.setLayout(new BorderLayout());

    this.topPanel.setPreferredSize(new Dimension(100, 100));
    this.centerPanel.setPreferredSize(new Dimension(100, 100));
    this.toggleButton.setPreferredSize(new Dimension(100, 100));

    this.add(topPanel, BorderLayout.NORTH);
    this.add(centerPanel, BorderLayout.CENTER);
    this.add(toggleButton, BorderLayout.SOUTH);

    this.toggleButton.addItemListener(new ItemListener() {
        @Override
        public void itemStateChanged(ItemEvent e) {
            if(e.getStateChange() == ItemEvent.SELECTED) {
                add(centerPanel, BorderLayout.CENTER);
            } else {
                remove(centerPanel);
            }
            pack();
        }
    });

    this.pack();
    this.setVisible(true);
}
}

您可以看到centerPanel仅实例化一次.

You can see that centerPanel is only instantiated once.

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