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我要放一个按扭 按下后画一条线 但是画不出
代码如下
package mine;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class java1
extends JFrame
implements ActionListener {
private JPanel panel;
private JButton button;
public static void main(String args[]) {
java1 frame = new java1();
frame.setSize(300,400);
frame.creatGUI();
frame.show();
}
private void creatGUI() {
Container window = getContentPane();
window.setLayout(new FlowLayout());
setDefaultCloseOperation(EXIT_ON_CLOSE);
panel = new JPanel();
panel.setPreferredSize(new Dimension(300,300));
window.add(panel);
button = new JButton("press me");
window.add(button);
}
public void actionPerformed(ActionEvent event) {
Graphics paper = panel.getGraphics();
paper.setColor(Color.WHITE);
paper.fillRect(0, 0, 300, 300);
paper.setColor(Color.RED);
paper.drawLine(0, 0, 300, 300);
}
}
是哪里错了? |
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