Java Swing在运行时添加/删除jButtons

Question

我的应用程序有一个模块,允许用户在运行时在jLayeredpane上添加jButton.我想为这个动态添加的内容添加动作侦听器,并且还必须提供在运行时删除动态添加的按钮的访问权限.有没有办法做到这一点？

private Map<String, JButton> dynamicButtons;

public void addButton(String name) {
    JButton b = new JButton(name);
    b.addActionListener(new java.awt.event.ActionListener() {

        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jButton1ActionPerformed(evt);
        }
    });

    jLayeredPane2.add(b);
    dynamicButtons.put(name, b);
    jLayeredPane2.invalidate();
}

public void removeButton(String name) {
    JButton b = dynamicButtons.remove(name);
    jLayeredPane2.remove(b);
    jLayeredPane2.invalidate();
}

Answer 1

原始答案 一般情况良好,但在这种情况下做的不同

为了跟踪任意数量的添加JButtons,您需要将它们保存在列表中.

因此,在创建新按钮,向其添加侦听器并将其添加到窗格后,您需要将该新按钮保存在列表中.

这样您就可以跟踪已添加的所有按钮.

您还可以使用Map<String, JButton>将按钮名称映射到按钮的按钮.

例:

private Map<String, JButton> dynamicButtons;

public void addButton(String name) {
    JButton b = new JButton(name);
    b.addActionListener(someAction);
    yourPanel.add(b);
    dynamicButtons.put(name, b);
    yourPanel.invalidate();
}

public void removeButton(String name) {
    Button b = dynamicButtons.remove(name);
    yourPanel.remove(b);
    yourPanel.invalidate();
}

以下是一个完整的类,可让您动态添加和删除按钮.这不完全是你想要的,但它应该让你非常接近.

针对您具体案例的代码:

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class ExampleFrame extends JFrame {

    private JButton add, remove;
    private JPanel dynamicButtonPane, addRemovePane;

    private boolean waitingForLocationClick;

    public ExampleFrame() {
        super("Dynamic button example");
        waitingForLocationClick = false;
        add = new JButton("Add Button");
        add.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                addButton(JOptionPane
                        .showInputDialog("Name of the new button:"));
            }
        });
        remove = new JButton("Remove Button");
        remove.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                lookingToRemove = true;
            }
        });
        JPanel mainPane = new JPanel(new BorderLayout());
        dynamicButtonPane = new JPanel();
        dynamicButtonPane.setLayout(null);
        dynamicButtonPane.setPreferredSize(new Dimension(300, 300));
        addRemovePane = new JPanel();
        addRemovePane.add(add);
        addRemovePane.add(remove);
        mainPane.add(dynamicButtonPane, BorderLayout.NORTH);
        mainPane.add(addRemovePane, BorderLayout.SOUTH);
        add(mainPane);
        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
        dynamicButtonPane.addMouseListener(pointSelectorListener);
    }

    private JButton buttonToPlace;

    public void addButton(String name) {
        JButton b = new JButton(name);
        b.setActionCommand(name);
        b.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (lookingToRemove) {
                    if (e.getSource() instanceof JButton) {
                        dynamicButtonPane.remove((Component) e.getSource());
                        dynamicButtonPane.validate();
                        dynamicButtonPane.repaint();
                    }
                } else
                    JOptionPane.showMessageDialog(ExampleFrame.this, "This is " + e.getActionCommand());
            }
        });
        waitingForLocationClick = true;
        lookingToRemove = false;
        buttonToPlace = b;
    }

    public void putButtonAtPoint(Point p) {
        System.out.println("Placing a button at: " + p.toString());
        dynamicButtonPane.add(buttonToPlace);
        buttonToPlace.setBounds(new Rectangle(p, buttonToPlace
                .getPreferredSize()));
        dynamicButtonPane.validate();
        buttonToPlace = null;
        waitingForLocationClick = false;
    }

    private boolean lookingToRemove = false;

    private final MouseListener pointSelectorListener = new MouseAdapter() {
        @Override
        public void mouseClicked(MouseEvent e) {
            if (waitingForLocationClick) {
                putButtonAtPoint(e.getPoint());
            } else {
                System.out.println("Not in waiting state");
            }
        }
    };

    public static void main(String[] args) {
        new ExampleFrame();
    }
}

Answer 2

绝对.所有这些东西都可以随时以编程方式完成.以下是一些避免问题和陷阱的提示:

• 向任何面板添加组件时,请确保在Event Dispatch Thread through上完成此操作SwingUtilities.invokeLater(Runnable).在Runnable中,您希望将组件添加到面板,连接侦听器以及重新布局面板.
• 使用SwingUtilities.isEventDispatchThread()来检查,看看是否已经在事件调度线程上.如果你是,那么你可以立即运行Runnable而不是调用invokeLater.
• 修改完面板布局后,请务必调用Component.invalidate()面板以确保再次布局.
• 维护自己的监听器列表.覆盖面板上的添加和删除方法,以从列表中添加或删除它们,也可以从所有现有按钮中添加或删除它们.添加新按钮时,请在列表中添加所有侦听器.

这是一项非常常见的任务,Java完全支持它.你应该能够毫不费力地完成它.