无法在JFrame上绘制

我正在尝试制作一个simle java程序，在鼠标定位时绘制一个圆圈，它获取鼠标X和Y坐标，但它没有绘制任何东西，我试图画一个字符串，一个圆圈和一条线，但没有任何工作，我改变了一些代码，但它仍然不起作用

class Test4 { public static String a; public static JFrame frame = new JFrame(); public static Point Gett(){ PointerInfo h = MouseInfo.getPointerInfo(); Point b = h.getLocation(); return b; } public void paintComponent(int x, int y, Graphics g) { g.drawOval(x, y, 10, 10); } public static void main(String[] args) throws InterruptedException { int h = 250; int f = 200; frame.setVisible(true); frame.setSize(h, f); frame.setLocationRelativeTo(null); while(true){ Point b = Gett(); int x = (int) b.getX(); int y = (int) b.getY(); System.out.println(x); System.out.println(y); frame.repaint();}}} 

Answer 1

• 不要直接在JFrame上执行自定义绘制 。 如果可以，请始终在覆盖paintComponent方法的JComponent上执行此操作。

• 不要为此目的使用无限循环。 MouseMotionListener用于鼠标移动侦听

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 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(); } } }