使用 Thread 在 Jpanel 对象上添加图形

Question

我想在这个程序中添加图形。图形将绘制在 "drawPanel" 对象上。我这里必须要用thread。

不知道用线程在 Jpanel 对象中绘图。在该 Jpanel 对象上绘制图形的有效方法是什么？

如何线程和 paintComponent() 去 interact.Thanks。

Code:

public class LinearSearch extends JPanel{

    private final Font LABEL_FONT = new Font("courier", Font.BOLD, 30);

    private JPanel mainPanel;
    private JPanel centerPanel;
    private JPanel inputPanel;
    private JPanel drawPanel;

    private JLabel lblTitle;
    private Button btnBack;

    public LinearSearch(JPanel mainPanel) {
        this.mainPanel = mainPanel;

        setBackground(Color.WHITE);

        initialize_All();
    }

    private void initialize_All() {
        lblTitle = new JLabel("\"Linear Search\"", SwingConstants.CENTER);
        lblTitle.setFont(LABEL_FONT);

        ///Center Panel
        centerPanel = new JPanel();
        centerPanel.setLayout(new BorderLayout());

        ///Input Panel
        inputPanel = new JPanel();
        inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.X_AXIS));


        ///Draw Panel
        drawPanel = new JPanel();
        drawPanel.setLayout(new FlowLayout());

        /// I want to add graphics on this drawPanel Jpanel

        btnBack = new Button("Back");
        btnBack.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent arg0) {
                setVisible(false);
                removeAll();

                mainPanel.add(new CatagoriesMenu(mainPanel));
            }
        });


        setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
        setLayout(new BorderLayout(10, 10));

        add(lblTitle, BorderLayout.PAGE_START);
        add(centerPanel, BorderLayout.CENTER);
        add(btnBack, BorderLayout.PAGE_END);

        centerPanel.add(inputPanel, BorderLayout.PAGE_START);
        centerPanel.add(drawPanel, BorderLayout.CENTER);

    }
}

Answer 1

I must need to add graphics on "drawPanel" Jpanel Object.

然后您需要扩展 JPanel 并重写 paintComponent(...) 方法来进行自定义绘制。

阅读 Custom Painting 上的 Swing 教程部分，了解更多信息和工作示例以帮助您入门。

Answer 2

只需要在 add() 方法中从另一个 class 添加这个 class 对象。

This will work (tested):

public class LinearSearchSimulation extends JPanel implements Runnable{

    private final int DELAY = 50;
    private JPanel mainPanel;

    int x=0, y=0;

    private Thread thread;
    private boolean threadFlag = false;

        public LinearSearchSimulation(JPanel mainPanel){
            this.mainPanel = mainPanel;
            setBackground(Color.WHITE);

        }

        public void start() {
            if (threadFlag) {
                return;
            }

            threadFlag = true;
            thread = new Thread(this);
            thread.start();
        }

        public void stop() {
            if (!threadFlag) {
                return;
            }

            threadFlag = false;
            try {
                thread.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.fillOval(x,y, 55, 55);
            g.dispose();
        }

        public void update() {

            x += 1;
            y += 1;
        }

        @Override
        public void run() {
            long beforeTime, timeDiff, sleep;

            beforeTime = System.currentTimeMillis();

            while (threadFlag) {

                update();
                repaint();

                timeDiff = System.currentTimeMillis() - beforeTime;
                sleep = DELAY - timeDiff;

                if (sleep < 0)
                    sleep = 2;
                try {
                    Thread.sleep(sleep);
                } catch (InterruptedException e) {
                    System.out.println("interrupted");
                }

                beforeTime = System.currentTimeMillis();
            }
        }

}

使用 Thread 在 Jpanel 对象上添加图形

Add graphics on a Jpanel Object with Thread

java

swing

jpanel

java-threads