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：
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
您正在创建2个AreaForText实例,这不是您想要做的.一个添加到JFrame,一个添加到侦听器.因此,实际获取鼠标事件并且正在调用重绘的那个与正在显示的对象不同.
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);
}
});
}
}
