What is drawpolygon() in Java?
Share
Overview
A polygon is a closed plane figure consisting of line segments joining more than one vertices.
The drawpolygon() method is a method of the Graphics class in Java that is used to draw polygons.
Syntax
drawpolygon(int[] x, int[] y, int numberOfPoints)
-
int[]x: It is an integer array consisting of x-coordinates of the required shape. -
int[]y: It is an integer array consisting of y-coordinates of the required shape. -
int numberOfPoints: It is an integer variable used to declare the number of vertices the figure will have.
Example
import java.awt.*;
import javax.swing.*;
class Main extends JPanel {
public void paintComponent(Graphics g) {
int [] x = {45, 55, 75, 55, 63, 43, 17, 31, 12, 35, 45};
int [] y = {41, 65, 71, 83, 108, 88, 105, 78, 61, 63,41};
g.drawPolygon(x, y, 10); // 10 vertices required to draw a star
}
public static void main( String args[] ) {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("Draw Polygon");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBackground(Color.white);
frame.setSize(300, 200);
Main panel = new Main();
frame.add(panel);
frame.setVisible(true);
}
}
Explanation
-
Line 1: We import the AWT API for making a GUI.
-
Line 2: We import the Swing API for making a GUI.
-
Line 4: We create a class and inherit it from JPanel.
-
Line 5: We override the
paintComponent()method of JPanel class. -
Line 6: We make an array of x-coordinates of points to draw a star.
-
Line 7: We make an array of y-coordinates of points to draw a star.
-
Line 8: We call the built-in
drawPolygon()method ofGraphicsclass to draw a star. It takes three parameters as array of x-coordinates, array of y-coordinates and total number of points of the shape drawn, respectively . -
Line 11: We override the
main()method. -
Line 12: Let the System handle the decoration (the borders) of the window. Using this, the window appeared will be a decorated one with fancy borders. This line is optional.
-
Line 13: We create an object of JFrame to create the window and set its name as “Draw Polygon”.
-
Line 14: This causes the window to close on receiving a close window event.
-
Line 15:We set the background color as white. This is optional.
-
Line 16: We set the window size.
-
Line 18: We create an object of
Mainclass. It will automatically call thepaintComponent()method (the one which we have to override). -
Line 20: We add this component (the drawn polygon) into the window.
-
Line 22: We make the window visible by setting the flag to
true.
