如何从JFrame中删除JPanel？ [英] How can I remove a JPanel from a JFrame?

问题描述

最近我在这里问了如何将新的JPanel添加到JFrame 。答案帮助我获得了一个有效的代码。但不是我有一个相关的问题：我怎样才能删除旧的JPanel。由于以下问题，我需要这样做。

Recently I asked here how to add a new JPanel to JFrame. The answer helped me to get a working code. But not I have a related question: "How can I remove an old JPanel". I need that because of the following problem.

当我想要时出现一个新的JPanel（超出时间限制或用户按下提交按钮）。但是在几秒钟内，旧JPanel的一些元素与新JPanel的组件一起出现。我不明白为什么会这样。

A new JPanel appears appears when I want (either time limit is exceeded or user press the "Submit" button). But in several seconds some element of the old JPanel appears together with the component of the new JPanel. I do not understand why it happens.

我认为这是因为我必须更新窗口的其他线程。但是第一个线程只添加一次旧面板（因此，它应该完成）。在第二个线程中，我有一个被打破的循环（所以，它也应该完成）。

I thought that it is because I have to other threads which update the window. But the first thread just add the old panel once (so, it should be finished). And in the second thread I have a loop which is broken (so, it also should be finished).

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();
            }
        });

    }
};

推荐答案

从中移除组件（面板）的最简单方法容器（框架）是保持对它的引用，然后调用 Container.remove（Component） ie：

the easiest way to remove a component (panel) from a container (frame) is to keep a reference to it, and then call 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();
        }
        });

}
};

我还没有测试过这段代码，但它应该有效。

i haven't tested this code but it should work.

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