import javax.swing.*;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.*;
import java.awt.Polygon;

public class PolygonTest1 extends JPanel{

  public static void main(String[] args){
    JFrame frame = new JFrame();

    PolygonTest1 app = new PolygonTest1();
    frame.getContentPane().add(app);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(10, 10, 300, 200);
    frame.setTitle("ƒ^ƒCƒgƒ‹");
    frame.setVisible(true);
  }

  public void paintComponent(Graphics g){
    Graphics2D g2 = (Graphics2D)g;

    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                        RenderingHints.VALUE_ANTIALIAS_ON);

    int[] xpoints = {30, 150, 170, 80, 30};
    int[] ypoints = {20, 40, 120, 140, 80};
    int npoints = xpoints.length;
    Polygon polygon = new Polygon(xpoints, ypoints, npoints);

    g2.draw(polygon);
  }
}