JFrame repaint()问题 – Java

我希望能够在JFrame上使用 Java的paint()进行绘制.当我单击JFrame(现在任何地方)时,我希望用点击的坐标重新绘制JFrame – 类似于这个Java小程序 http://www.realapplets.com/tutorial/MouseClickExample.html

正在工作：

>最初绘制所有内容并正确显示JFrame

不工作：

>即使声明了repaint(),JFrame也不会重新绘制和更新

这是我的代码 – 请尽可能严格地使用它 – 我想改进我的Java编程技术(如果你有时间)指出我可以改进的每个方面.

任何帮助将非常感谢.

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

class AreaForText extends JPanel implements MouseListener {

int xpos; 
int ypos;

JFrame myJFrame = new JFrame();

public void setJFrame() {

    myJFrame.setSize(300,150);
    myJFrame.setTitle("Bigger Text!");
    myJFrame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
    myJFrame.setVisible(true);
    myJFrame.getContentPane().add(new AreaForText());
    myJFrame.addMouseListener(new AreaForText());

}

public void mouseClicked(MouseEvent me) {
    //Save the coordinates of the click lke this. 
    xpos = MouseInfo.getPointerInfo().getLocation().x; 
    ypos = MouseInfo.getPointerInfo().getLocation().y;
    System.out.print("Click" + "  x: " + xpos + "  y: " + ypos);
    myJFrame.invalidate();
    repaint();
    revalidate();
}


public void mouseEntered(MouseEvent e){
}

public void mouseReleased(MouseEvent e) { 
}

public void mousePressed(MouseEvent e) {
}

public void mouseExited(MouseEvent e) { 
}

public void paint(Graphics g) {

    System.out.print("hello");
    g.drawString("Hello World",30,80);
    g.fillRect(20,20,20);        
    g.drawString("("+xpos+","+ypos+")",xpos,ypos);

    }
}

class EnlargeText {

    public static void main(String args[]) {

       AreaForText test = new AreaForText();

       test.setJFrame();

    }

 }

解决方法

你的一些代码组织并不是最好的.你有一个JPanel子类,它构建自己的JFrame并将自己放入面板中.如果你真的需要它,你应该传入JFrame.我在下面做了一些改动.

编辑.我修复了一些鼠标监听器的东西,你得到了错误的X / Y坐标,而且,你应该直接将监听器添加到面板,而不是JFrame,这样你就不必翻译坐标.

编辑我将paint方法更改为paintComponent,这是在此处覆盖的首选方法.有关更多信息,请查看Swing Paint Tutorial.

import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.MouseInfo;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.JFrame;
import javax.swing.JPanel;

class AreaForText extends JPanel implements MouseListener {

    private int xpos;
    private int ypos;


    public AreaForText() {
        super();
        this.addMouseListener(this);
    }

    public void mouseClicked(MouseEvent me) {
        // Save the coordinates of the click lke this.
        xpos = me.getX();
        ypos = me.getY();
        System.out.print("Click" + "  x: " + xpos + "  y: " + ypos);
        repaint();
    }

    public void mouseEntered(MouseEvent e) {
    }

    public void mouseReleased(MouseEvent e) {
    }

    public void mousePressed(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        System.out.print("hello");
        g.drawString("Hello World",80);
        g.fillRect(20,20);
        g.drawString("(" + xpos + "," + ypos + ")",ypos);

    }
}

class EnlargeText {

    public static void main(String args[]) {

        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame myJFrame = new JFrame("Bigger Text!");
                myJFrame.setSize(300,150);
                myJFrame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
                myJFrame.getContentPane().add(new AreaForText());
                myJFrame.setVisible(true);
            }
        });
    }

}

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