Question

完成搜索，我真的没有看到这个棘手问题的匹配答案。

我来了，伙计们。感谢您的帮助。

我试图通过使用actionlistener在JPanel的按钮中调用JPanel; 虽然它添加的第一个按钮工作正常，但它不适用于其他两个按钮; 在第一个按钮和其余两个按钮中调用的jpanel之间的区别是，第一个按钮调用当前Jpanel的另一个Jpanel;但另外两个叫目前的Jpanels中有两个私人的jpanel。

我在做什么：我正在尝试在同一个Jpanel中使用显示两个不同的图表两个按钮，可互换;私人jpanels纯粹用于绘制图表;我想我只需要在不同的按钮中调用这两个jpanel，而无需创建一个全新的JPanel 包含每个jpanel以绘制图表，然后像在第一个按钮中调用另一个jpanel一样调用它们。

为我笨拙的措辞道歉......代码也有。

公共类ExamPerf扩展了JPanel {

final JPanel viewPerf = TabbedQuiz.viewPerfPanel;

final ChartsPanel CP = new ChartsPanel（）;

//我在构造函数中构建jpanel;所有按钮都在这里;

          public ExamPerf() {
    setBackground(Color.BLACK);

    setBounds(0, 0, 728, 380);
    setLayout(null);

    setBorder(BorderFactory.createLineBorder(Color.ORANGE, 10));
    setBorder(BorderFactory.createTitledBorder(
            BorderFactory.createLineBorder(Color.ORANGE),
            "Exam Performance", 0, 0, new Font("Tahoma", Font.BOLD, 15),
            Color.WHITE));

    DrawCurrent drawarea=new DrawCurrent();
    add(drawarea);

//这是第一个按钮，调用另一个Jpanel，一个完全不同的类;

    JButton backBut = new JButton("Main Menu");
    backBut.setFont(new Font("Tahoma", Font.BOLD, 11));
    backBut.setBounds(10, 24, 93, 23);
    add(backBut);
    backBut.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            // TODO Auto-generated method stub

            setVisible(false);
            invalidate();
            viewPerf.add(CP);

        }
    });

//这是第二个按钮，我试图调用私有类DrawCurrent; //但它不起作用;我的想法是，

    JButton histoPerf = new JButton("Historical Performance");
    histoPerf.setFont(new Font("Tahoma", Font.BOLD, 11));
    histoPerf.setBounds(122, 24, 161, 23);
    add(histoPerf);
    histoPerf.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent arg0) {
            // TODO Auto-generated method stub
            setVisible(false);

            invalidate();

            DrawCurrent drawplace=new DrawCurrent();


            add(drawplace, BorderLayout.CENTER);




        }
    });

//这是第三个按钮，同样的问题。

          JButton currentPerf = new JButton("Current Performance");
    currentPerf.setFont(new Font("Tahoma", Font.BOLD, 11));
    currentPerf.setBounds(303, 24, 151, 23);
    add(currentPerf);
    currentPerf.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent arg0) {
            // TODO Auto-generated method stub

            setVisible(true);
            invalidate();

            DrawHistorical drawHis=new DrawHistorical();
            add(drawHis);




        }
    });

}

//这是第一个私有类，DrawCurrent;

公共类DrawCurrent扩展了JPanel {

    public DrawCurrent() {
        setBackground(Color.BLACK);
        setForeground(null);

        setBounds(10, 49, 708, 320);

        setBorder(BorderFactory.createLineBorder(Color.ORANGE, 10));
        setBorder(BorderFactory.createTitledBorder(
                BorderFactory.createLineBorder(Color.ORANGE), "Chart", 0,
                0, new Font("Tahoma", Font.BOLD, 15), Color.WHITE));
        setLayout(null);

    }

    @Override
    public void paintComponent(Graphics g) {
        final Graphics2D canvas = (Graphics2D) g;
        final BasicStroke Pen = new BasicStroke(4, BasicStroke.CAP_ROUND,
                BasicStroke.JOIN_ROUND);

        canvas.setStroke(Pen);
        canvas.setColor(Color.LIGHT_GRAY);
        canvas.drawLine(5, 315, 703, 315);
        canvas.drawLine(getWidth() / 2, 700, getWidth() / 2, 19);

        // write the names of columns on top of them;
        canvas.setFont(new Font("Times New Roman", Font.BOLD, 13));
        canvas.drawString("Right", 50, 100);
        canvas.drawString("Wrong", getWidth() / 2 + 150, 300);

        // draw two 3D rectangles as the columns of the performances;
        //
        canvas.fill3DRect(50, 100, 40, 215, true);
        canvas.fill3DRect(getWidth() / 2 + 150, 300, 40, 15, true);

    }

}

//这是第二个私有类，DrawHistorical;

私有类DrawHistorical扩展了JPanel {

    final ArrayList<Integer> examCount=new ArrayList<>();

    final int leftEdge=10;

    public DrawHistorical() {
        setBackground(Color.BLACK);
        setForeground(null);

        setBounds(leftEdge, 49, 708, 320);

        setBorder(BorderFactory.createLineBorder(Color.ORANGE, 10));
        setBorder(BorderFactory.createTitledBorder(
                BorderFactory.createLineBorder(Color.ORANGE), "Chart", 0,
                0, new Font("Tahoma", Font.BOLD, 15), Color.WHITE));
        setLayout(null);

    }

    @Override
    public void paintComponent(Graphics g) {
        final Graphics2D canvas = (Graphics2D) g;
        final BasicStroke Pen = new BasicStroke(2, BasicStroke.CAP_ROUND,
                BasicStroke.JOIN_ROUND);

        canvas.setStroke(Pen);
        canvas.setColor(Color.LIGHT_GRAY);
        canvas.setFont(new Font("Times New Roman", Font.BOLD, 13));

        //this loop is to draw the graph of the historical performance of completed exams.
        for(int i=0; i<examCount.size();i=i+3){

            // write the number of exam on top of the lien graph.

        canvas.drawString("Ex"+examCount.get(i).toString(), leftEdge+i, examCount.get(i));

            // draw the line graph and extends as long as the number of completed exams increases.

        canvas.drawLine(leftEdge+2+i, examCount.get(i), leftEdge+3+i, examCount.get(i+1));

        }



    }

}

非常感谢你们，任何不清楚的事请把它们扔给我。

Answer 1

欢迎使用Stack Overflow。这里有一些规则 - 我在这里待了很长时间，我心不在焉:)但我还记得一个叫做SSCE的东西。一个简单，独立的示例，确保您从每个人那里获得大量答案。

1）实际问题是你在动作监听器中创建了新面板：

public void actionPerformed(ActionEvent arg0) {
    setVisible(false);
    invalidate();
    DrawCurrent drawplace=new DrawCurrent();
    add(drawplace, BorderLayout.CENTER);
}

在这里做些奇怪的事情。

1）setVisible（false）会隐藏屏幕上的内容 - 不是我认为的面板，而是外面板。

2）您创建一个新的DrawCurrent实例，并添加到布局中，而不是隐藏其他面板并使该面板可见。

正确的逻辑是：在ExamPerf类中同时创建DrawCurrent和DrawHistorical实例，在其布局中添加add：

DrawCurrent current;
DrawHistorical historical;

public ExamPerf() extends JPanel {
    current=new DrawCurrent();
    historical=new Historical();
    add(current); // TODO you may need further layout settings here
    add(historical);  // TODO you may need further layout settings here
    current.setVisible(true);
    historical.setVisible(false);
}

在按钮监听器中，只需更改图表面板的可见属性：

public void actionPerformed(ActionEvent arg0) {
    current.setVisible(false); 
    history.setVisible(true);
}

（对于另一个按钮也是如此，这使得true和false显示另一个面板）。

或者，请考虑使用旨在解决此问题的CardLayout，而不是实施您自己的解决方法。

https://docs.oracle.com/javase/tutorial/uiswing/layout/card.html

无法在JPanel的按钮内调用JPanel

1 个答案: