import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.BorderFactory;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseMotionAdapter;public class SwingPaintDemo3 { public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
} private static void createAndShowGUI() {
System.out.println("Created GUI on EDT? "
+ SwingUtilities.isEventDispatchThread());
JFrame f = new JFrame("Swing Paint Demo");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MyPanel());
f.pack();
f.setVisible(true);
}
}class MyPanel extends JPanel { private int squareX = 50;
private int squareY = 50;
private int squareW = 20;
private int squareH = 20; public MyPanel() { setBorder(BorderFactory.createLineBorder(Color.black)); addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
moveSquare(e.getX(), e.getY());
}
}); addMouseMotionListener(new MouseAdapter() {
public void mouseDragged(MouseEvent e) {
moveSquare(e.getX(), e.getY());
}
}); } private void moveSquare(int x, int y) {
int OFFSET = 1;
if ((squareX != x) || (squareY != y)) {
repaint(squareX, squareY, squareW + OFFSET, squareH + OFFSET);
squareX = x;
squareY = y;
repaint(squareX, squareY, squareW + OFFSET, squareH + OFFSET);
}
} public Dimension getPreferredSize() {
return new Dimension(250, 200);
} protected void paintComponent(Graphics g) {
super.paintComponent(g); g.drawString("This is my custom Panel!", 10, 20);
g.setColor(Color.RED);
g.fillRect(squareX, squareY, squareW, squareH);
g.setColor(Color.BLACK);
g.drawRect(squareX, squareY, squareW, squareH);
}
}直接上了代码 问题是moveSquare方法为什么要调用两次的repaint方法呢? super.paintComponent方法上网查了下说是可以清除所有东西 那moveSquare方法的第一个repaint方法不是多余的了吗? 不解啊。
解决方案 »
- 一个关于成员内部类的问题?外部类无法通过方法修改内部类变量?迷惑
- java中线程 问题 !! 求高手解答!!
- 读文件问题
- OutputStream的方法void write(int b)为什么不设计成void write(byte b)呢?
- 我想写一个简单的ATM自动提款机系统,怎么开始呢?
- 想做这么一个Dilog(最后给个例子看看)
- 关于WSAD建立CMP的findBy...方法后在建立查询描述语句时的问题!急!!!
- 关于用socket实现上传和下载,请帮忙
- 如何将int[]转换成image对象?
- 索源码----网吧管理
- 大家麻烦帮看下 jdbc 问题 运行也不抱错误也没什么反应 控制台什么也不显示
- 帮小妹看看这个是什么问题?或你有更好方法解决(谁的方法最好,我会把100分直接送你))
郁闷