DrawPolygon – 源码巴士

import javax.swing.JFrame;
import javax.swing.JPanel;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Polygon;

public class DrawPolygon extends JFrame {
   public DrawPolygon() {
       add(new PolygonPanel());
   }

   /** Main method */
   public static void main(String[] args) {
       DrawPolygon frame = new DrawPolygon();
       frame.setTitle("DrawPolygon");
       frame.setSize(300, 200);
       frame.setLocationRelativeTo(null); //Center the frame
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
   }
}

//Draw a polygon in the panel
class PolygonPanel extends JPanel {
   protected void paintComponent(Graphics g) {
       int xCenter = getWidth() / 2;
       int yCenter = getHeight() / 2;
       int radius = Math.min(getWidth(), getHeight()) / 2;

       int[] xPoints = new int[6];
       int[] yPoints = new int[6];
       int nPoints = 6;

       for(int i = 0; i < nPoints; i++) {
           xPoints[i] = (int)(xCenter + radius * Math.cos(Math.PI / 3 * i));
           yPoints[i] = (int)(yCenter + radius * Math.sin(Math.PI / 3 * i));
       }

       // Create a Polygon object
       Polygon polygon = new Polygon(xPoints, yPoints, nPoints);

       super.paintComponent(g);

       // Draw the polygon
       g.setColor(Color.RED);
       g.drawPolygon(polygon);
   }
}