在这种情况下,不仅为paintComponent
JPanel 覆盖您的方法很重要,而且您还需要存储有关要绘制的圆圈的信息。paintComponent
在通话期间,您可以使用存储的信息在屏幕上绘制所有圆圈。
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class TempProject extends JPanel{
/** Stores info about circles */
public ArrayList<CircleInfo> circles = new ArrayList<CircleInfo>();
/** fields that were in example code */
public int count = 0;
public final int radius = 20;
public final int clients = 20;
public TempProject(){
addMouseListener(new MouseAdapter(){
@Override
public void mouseClicked(MouseEvent evt) {
count += 1;
if (count <= clients) {
// Store info about the circle to draw
circles.add(new CircleInfo(evt.getX() - (radius / 2), evt.getY() - (radius / 2), radius));
// Tell swing to repaint asap
repaint();
}
}});
}
@Override
public void paintComponent(Graphics g ) {
super.paintComponent(g);
//Iterates through saved circles and paints them
for(CircleInfo circle : circles){
g.drawOval(circle.x - circle.radius, circle.y - circle.radius, 2 * circle.radius, 2 * circle.radius);
g.setColor(Color.BLACK);
g.fillOval(circle.x - circle.radius, circle.y - circle.radius, 2 * circle.radius, 2 * circle.radius);
}
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setContentPane(new TempProject());
frame.setPreferredSize(new Dimension(400, 300));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
/** Simple class for storing Circle info */
public static class CircleInfo{
int x = 0;
int y = 0;
int radius = 0;
public CircleInfo(int x, int y, int radius){
this.x = x; this.y = y; this.radius = radius;
}
}
}