将多个项目绘制到JPanel

Question

我正在尝试使用两个简单的按钮创建一个JPanel.第一个按钮RoachComponent使面板中的组件数量加倍.第二个按钮将清除所有蟑螂.

现在,我的大部分计划都在运作,但是存在一个相当严重的问题.每次点击只添加一个蟑螂,即使它应该添加几千只蟑螂.我已经测试了所有我能想到的东西,但它仍然在逃避我.即使我手动添加两个蟑螂,也只显示一个.这是我的main函数中的代码.我99%确定代码的其他部分都是正确的,尽管如果需要我可以发布它.

final JFrame frame = new JFrame();
    final JPanel panel = new JPanel();
    // Button to create a new roach
    JButton button = new JButton("New Roach");

    final RoachPopulation roachPopulation = new RoachPopulation(2);

    // The label for displaying the results
    final JLabel label = new JLabel("Population: " + roachPopulation.getPopulation());

    // ActionListener class
    class doubleListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {

            System.out.println("------------------");
            for (int i = 0; i < roachPopulation.getPopulation(); i++) {
                RoachComponent newRoach = new RoachComponent();
                panel.add(newRoach);
                newRoach.getCoords();
            }
            panel.repaint();
            frame.repaint();
            roachPopulation.doublePopulation();
            label.setText("Population: " + roachPopulation.getPopulation());
            // Showing that there *is* the correct number of roaches in the panel.
            System.out.println(panel.getComponentCount());
        }
    }
    RoachComponent r1 = new RoachComponent();
    RoachComponent r2 = new RoachComponent();
    panel.setLayout(new BorderLayout());
    panel.add(button, BorderLayout.SOUTH);
    panel.add(label, BorderLayout.NORTH);
    panel.add(r1);
    panel.add(r2);
    //panel.add(component, BorderLayout.CENTER);
    frame.add(panel);

    frame.repaint();

    ActionListener doubleListener = new doubleListener();
    button.addActionListener(doubleListener);

    frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);

}

Answer 1

• 删除以前frame.repaint();添加的所有代码panel.revalidate()jpanel.repaint();

• (最终的样子)一切都取决于二手LayoutManager的JPanel

• 为了更好的帮助更快的帖子和SSCCE

• 这篇文章会对你有帮助