paintComponent（）永远不会在JFrame上执行
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.*; 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; import java.awt.geom.*; import java.util.*; public class test1 extends JFrame implements MouseListener { private JPanel JP = new JPanel(); public test1() { JP.setBorder(BorderFactory.createLineBorder(Color.black)); JP.addMouseListener(this); this.setDefaultCloseOperation(this.EXIT_ON_CLOSE); this.add(JP); this.pack(); } public static void main(String[] args) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { test1 frame = new test1(); frame.setSize(400,400); frame.setVisible(true); } }); } public void mouseClicked(MouseEvent e) { //drawCircle(e.getX(), e.getY()); //repaint(); ballball ball; ball = new ballball(); //ball.paintComponent(Graphics g); System.out.println("ballball"); } public void mouseExited(MouseEvent e) { } public void mousePressed(MouseEvent e) { //this.mouseX=e.getX(); //this.mouseY=e.getY(); } public void mouseReleased(MouseEvent e) { } public void mouseEntered(MouseEvent e) { } } class ballball extends test1 implements Runnable { private int squareX = 50; private int squareY = 50; private int squareW = 100; private int squareH = 100; public boolean draw; private Vector v = new Vector(); public ballball() { /*addMouseListener(new MouseAdapter() { public void mousePressed(MouseEvent e) { draw = true; //Thread thread1 = new Thread(this.moveSquare(50, 50)); repaint(); //moveSquare(e.getX(),e.getY()); } });*/ /*addMouseMotionListener(new MouseAdapter() { public void mouseDragged(MouseEvent e) { moveSquare(e.getX(),e.getY()); } });*/ System.out.println("ball created"); this.repaint(); } public void run() { } 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 void paint(Graphics g) { g.drawString("abcasdfasffasfas", 10, 10); } //@Override public void paintComponent(Graphics g) { //if (draw) { // existing code System.out.println("paint"); //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); Shape circle = new Ellipse2D.Float(squareX,squareY,100f,100f); Graphics2D ga = (Graphics2D)g; ga.draw(circle); //} } }
该程序的目的是单击创建圆，球类扩展test1，当test1检测到鼠标单击时，创建球球对象。 但是永远不会执行paint / paintComponent方法。 在我的程序结构中，是否可以将圆圈绘制到超类JPanel？
JFrame不是JComponent ，它没有可以覆盖的paintComponent方法。 相反，您可以扩展JPanel并将其添加到框架中。