java - 不使用 repaint()、revalidate() 刷新 GUI

Question

我有一个带有多个面板的框架。每当我按下/释放/单击中心面板时，JLabel 都会显示我执行此类操作的次数和坐标。问题是窗口不会刷新，因此 JLabel 上的所有这些值都保持为 0。通常对于 PaintComponents，我会使用 repaint()，但我没有使用此方法。

这是我应该“重新绘制”的代码段:

public void mousePressed(MouseEvent e) {
    pressCounter++;
    x = e.getX();
    y = e.getY();
    buildIt(); //this works, but doesn't do what i want it to do
}

调用buildIt()实际上是有效的，但它会在每次操作后打开一个新窗口，而不是刷新原始窗口。我还在这里尝试了 revalidate() 和 removeAll()，但它们似乎根本没有做任何事情。

那么如何刷新窗口？

以下是完整的代码供引用:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class MouseMonitor extends JPanel implements MouseListener {
    JFrame frame;
    JPanel topPanel, centerPanel, bottomPanel;
    JLabel pressLabel, releaseLabel, clickLabel, xLabel, yLabel;

    int pressCounter = 0;
    int releaseCounter = 0;
    int clickCounter = 0;

    int x, y;

    void buildIt() {
        frame = new JFrame("Mouse Monitor");
        topPanel = new JPanel();
        centerPanel = new JPanel();
        bottomPanel = new JPanel();
        pressLabel = new JLabel("pressed: " + pressCounter);
        releaseLabel = new JLabel("released: " + releaseCounter);
        clickLabel = new JLabel("clicked: " + clickCounter);
        xLabel = new JLabel("x-coordinate: " + x);
        yLabel = new JLabel("y-coordinate: " + y);

        frame.add(topPanel, BorderLayout.NORTH);
        frame.add(centerPanel, BorderLayout.CENTER);
        frame.add(bottomPanel, BorderLayout.SOUTH);
        topPanel.add(pressLabel);
        topPanel.add(releaseLabel);
        topPanel.add(clickLabel);
        bottomPanel.add(xLabel);
        bottomPanel.add(yLabel);
        pressLabel.setBorder(BorderFactory.createLineBorder(Color.WHITE));
        releaseLabel.setBorder(BorderFactory.createLineBorder(Color.WHITE));
        clickLabel.setBorder(BorderFactory.createLineBorder(Color.WHITE));
        xLabel.setBorder(BorderFactory.createLineBorder(Color.WHITE));
        yLabel.setBorder(BorderFactory.createLineBorder(Color.WHITE));

        Color color = new Color(193, 236, 255);
        centerPanel.setBackground(color);
        centerPanel.addMouseListener(this);

        frame.setSize(300, 300);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void mousePressed(MouseEvent e) {
        pressCounter++;
        x = e.getX();
        y = e.getY();
        buildIt();
    }

    public void mouseReleased(MouseEvent e) {
        releaseCounter++;
    }

    public void mouseClicked(MouseEvent e) {
        clickCounter++;
    }

    public void mouseEntered(MouseEvent e) { }
    public void mouseExited(MouseEvent e) { }

    public static void main(String[] args) {
        new MouseMonitor().buildIt();
    }
}

Answer 1

您不需要调用built()方法来刷新框架或面板。为了达到您想要的目的，您只需更改标签上的文字即可。例如，考虑 mousePressed(MouseEvent e) 方法，取出 buildIt() 方法:

    public void mousePressed(MouseEvent e) {
        pressCounter++;
        pressLabel.setText("pressed: " + pressCounter);

    }

对每个方法都执行此操作，您就可以开始了。在 main 方法中维护代码。