在jframe上画圈

Question

我必须画没有线的正方形，而是在那一角画点 如果您要搜索更滑的拼图板，则可以找到更多

我尝试制作正方形

 import javax.swing.*;
 import java.awt.*;
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
 public class Puzzle extends JFrame {
   private int x;
   private int y;
   public void paint(Graphics g){
     super.paint(g);
     g.setColor(Color.BLACK);
     Graphics2D graphics2D = (Graphics2D) g;
     //g.fillRect(0,0,100,100);
     while(x<400) {
        g.drawLine(x, 0, x, 400);
        x += 20;
     }
     while(y<400) {
        g.drawLine(0, y ,400,y);
        y += 20;
     }


  }

    public Puzzle(){
     setSize(400,400);
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     setVisible(true);
     setLayout(new GridLayout());

   }

    public static void main(String[] args){
        Puzzle puzzle = new Puzzle();

   } 

  }

它看起来像更滑的拼图板