如何从JFrame删除JPanel？

Z时代
2024-01-10
分类：问答

当我需要时会出现一个新的JPanel（超过了时间限制或用户按下了“提交”按钮）。但是几秒钟后，旧的JPanel的某些元素就会与新的JPanel的组件一起出现。我不明白为什么会这样。

我以为是因为我必须对其他线程更新窗口。但是第一个线程只需将旧面板添加一次（因此，应该完成）。在第二个线程中，我有一个中断的循环（因此，它也应该完成）。

这是我的代码：

private Thread controller = new Thread() {
    public void run() {
        // First we set the initial pane (for the selection of partner).
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                frame.getContentPane().add(generatePartnerSelectionPanel());
                frame.invalidate();
                frame.validate();
            }
        });
        // Update the pane for the selection of the parnter.
        for (int i=40; i>0; i=i-1) {
            final int sec = i;
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    timeLeftLabel.setText(sec + " seconds left.");
                }
            });
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) { }
            if (partnerSubmitted) {
                break;
            }
        }
        // For the given user the selection phase is finished (either the time is over or form was submitted).
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                frame.getContentPane().add(generateWaitForGamePanel());
                frame.invalidate();
                frame.validate();
            }
        });
    }
};

回答：

从容器（框架）中删除组件（面板）的最简单方法是保留对其的引用，然后调用Container.remove(Component)ie：

private Thread controller = new Thread() {
public void run() {
        final Component panel1 = generatePartnerSelectionPanel();
        // First we set the initial pane (for the selection of partner).
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                frame.getContentPane().add(panel1);
                frame.invalidate();
                frame.validate();
        }
        });
        // Update the pane for the selection of the parnter.
        for (int i=40; i>0; i=i-1) {
            final int sec = i;
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    timeLeftLabel.setText(sec + " seconds left.");
                }
            });
            try {Thread.sleep(1000);} catch (InterruptedException e) {}
            if (partnerSubmitted) {break;}
        }
        // For the given user the selection phase is finished (either the time is over or form was submitted).
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                frame.getContentPane().remove(panel1);
                frame.getContentPane().add(generateWaitForGamePanel());
                frame.invalidate();
                frame.validate();
        }
        });
}
};