不要直接在上执行自定义绘画
Jframe
。如果可以，请始终在JComponent
替代paintComponent
方法上进行操作。为此，请勿使用无限循环。有
MouseMotionListener
用于Mouse Motion收听的
public class Test4 { public static String a; public static CustomDrawingPanel content; public static Jframe frame = new Jframe(); final static int OVAL_WIDTH = 10; final static int OVAL_HEIGHT = 10; static int x = -20, y = -20; public static MouseMotionListener listener = new ContentListener(); public static void main(String[] args) throws InterruptedException { int h = 250; int f = 200; frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); content = new CustomDrawingPanel(); content.addMouseMotionListener(listener); frame.add(content); frame.getContentPane().setPreferredSize(new Dimension(h, f)); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } //class that performs custom drawing static class CustomDrawingPanel extends JPanel { public void paintComponent(Graphics g) { super.paintComponent(g); //Always call this g.drawOval(x, y, 10, 10); } } //listener to the mouse motion static class ContentListener implements MouseMotionListener { @Override public void mouseDragged(MouseEvent e) { mouseMoved(e); //if you delete this line, when you drag your circle will hang } @Override public void mouseMoved(MouseEvent e) { x = e.getX() - OVAL_WIDTH / 2; y = e.getY() - OVAL_HEIGHT / 2; content.repaint(); } }}
