Draw a Polygon in Java Applet

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Polygon is a closed figure with finite set of line segments joining one vertex to the other. The polygon comprises of set of (x, y) coordinate pairs where each pair is the vertex of the polygon. The side of the polygon is the line drawn between two successive coordinate pairs and a line segment is drawn from the first pair to the last pair.

We can draw Polygon in java applet by three ways :

drawPolygon(int[] x, int[] y, int numberofpoints) : draws a polygon with the given set of x and y points.

// Java program to draw polygon using
// drawPolygon(int[] x, int[] y, int numberofpoints)
// function
import java.awt.*;
import javax.swing.*;
  
public class poly extends JApplet {
  
    // called when applet is started
    public void init()
    {
        // set the size of applet to 300, 300
        setSize(200, 200);
        show();
    }
  
    // invoked when applet is started
    public void start()
    {
    }
  
    // invoked when applet is closed
    public void stop()
    {
    }
  
    public void paint(Graphics g)
    {
        // x coordinates of vertices
        int x[] = { 10, 30, 40, 50, 110, 140 };
  
        // y coordinates of vertices
        int y[] = { 140, 110, 50, 40, 30, 10 };
  
        // number of vertices
        int numberofpoints = 6;
  
        // set the color of line drawn to blue
        g.setColor(Color.blue);
  
        // draw the polygon using drawPolygon function
        g.drawPolygon(x, y, numberofpoints);
    }
}

Output :

drawPolygon(Polygon p) : draws a polygon with the given object of Polygon class.

// Java program to draw polygon
// using drawPolygon(Polygon p)
// function
import java.awt.*;
import javax.swing.*;
  
public class poly extends JApplet {
  
    // called when applet is started
    public void init()
    {
        // set the size of applet to 300, 300
        setSize(200, 200);
        show();
    }
  
    // invoked when applet is started
    public void start()
    {
    }
  
    // invoked when applet is closed
    public void stop()
    {
    }
  
    public void paint(Graphics g)
    {
        // x coordinates of vertices
        int x[] = { 10, 30, 40, 50, 110, 140 };
  
        // y coordinates of vertices
        int y[] = { 140, 110, 50, 40, 30, 10 };
  
        // number of vertices
        int numberofpoints = 6;
  
        // create a polygon with given x, y coordinates
        Polygon p = new Polygon(x, y, numberofpoints);
  
        // set the color of line drawn to blue
        g.setColor(Color.blue);
  
        // draw the polygon using drawPolygon
        // function using object of polygon class
        g.drawPolygon(p);
    }
}

Output :

drawLine(int x, int y, int x1, int y1) : In this method we would connect adjacent vertices with a line segment and also connect the first and last vertex.

// Java code to draw a polygon
// using  drawLine(int x, int y, int x1, int y1)
// function
import java.awt.*;
import javax.swing.*;
  
public class poly extends JApplet {
  
    // called when applet is started
    public void init()
    {
        // set the size of applet to 300, 300
        setSize(200, 200);
        show();
    }
  
    // invoked when applet is started
    public void start()
    {
    }
  
    // invoked when applet is closed
    public void stop()
    {
    }
  
    public void paint(Graphics g)
    {
        // x coordinates of vertices
        int x[] = { 10, 30, 40, 50, 110, 140 };
  
        // y coordinates of vertices
        int y[] = { 140, 110, 50, 40, 30, 10 };
  
        // number of vertices
        int numberofpoints = 6;
  
        // set the color of line drawn to blue
        g.setColor(Color.blue);
  
        // join the adjacent vertices
        for (int i = 0; i < numberofpoints - 1; i++)
            g.drawLine(x[i], y[i], x[i + 1], y[i + 1]);
  
        // join the first and last vertex
        g.drawLine(x[0], y[0], x[numberofpoints - 1], y[numberofpoints - 1]);
    }
}

Output :

Note: The above function are a part of java.awt package and belongs to java.awt.Graphics class. Also, these codes might not run in an online compiler please use an offline compiler. The x and y coordinates can be changed by the programmer according to their need