Java Language Tutorial - 2D Graphics in Java

Java Language

Introduction

Graphics are visual images or designs on some surface, such as a wall, canvas, screen, paper, or stone to inform, illustrate, or entertain. It includes: pictorial representation of data, as in computer-aided design and manufacture, in typesetting and the graphic arts, and in educational and recreational software. Images that are generated by a computer are called computer graphics.

The Java 2D API is powerful and complex. There are multiple ways to do 2D graphics in Java.

Example 1: Draw and Fill a Rectangle Using Java

This is an Example which print rectangle and fill color in the rectangle. https://i.stack.imgur.com/dlC5v.jpg

Most methods of the Graphics class can be divided into two basic groups:

Draw and fill methods, enabling you to render basic shapes, text, and images
Attributes setting methods, which affect how that drawing and filling appears

Code Example: Let us start this with a little example of drawing a rectangle and filling color in it. There we declare two classes, one class is MyPanel and other Class is Test. In class MyPanel we use drawRect( ) & fillRect( ) mathods to draw rectangle and fill Color in it. We set the color by setColor(Color.blue) method. In Second Class we Test our graphic which is Test Class we make a Frame and put MyPanel with p=new MyPanel() object in it.By running Test Class we see a Rectangle and a Blue Color Filled Rectangle.

First Class: MyPanel

import javax.swing.*;
import java.awt.*;
// MyPanel extends JPanel, which will eventually be placed in a JFrame
public class MyPanel extends JPanel { 
    // custom painting is performed by the paintComponent method
    @Override
    public void paintComponent(Graphics g){
        // clear the previous painting
        super.paintComponent(g);
        // cast Graphics to Graphics2D
        Graphics2D g2 = (Graphics2D) g;
        g2.setColor(Color.red); // sets Graphics2D color
        // draw the rectangle
        g2.drawRect(0,0,100,100); // drawRect(x-position, y-position, width, height)
        g2.setColor(Color.blue);
        g2.fillRect(200,0,100,100); // fill new rectangle with color blue
    } 
}

Second Class: Test

import javax.swing.;
import java.awt.;    
public class Test { //the Class by which we display our rectangle    
    JFrame f;    
    MyPanel p;    
    public Test(){    
        f = new JFrame();    
        // get the content area of Panel.    
        Container c = f.getContentPane();    
        // set the LayoutManager
        c.setLayout(new BorderLayout());        
        p = new MyPanel();    
        // add MyPanel object into container    
        c.add(p); 
        // set the size of the JFrame
        f.setSize(400,400);    
        // make the JFrame visible
        f.setVisible(true);    
        // sets close behavior; EXIT_ON_CLOSE invokes System.exit(0) on closing the JFrame
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    
    }       
    
    public static void main(String args[ ]){    
        Test t = new Test();     
    } 
}

For More Explanation about Border Layout: https://docs.oracle.com/javase/tutorial/uiswing/layout/border.html

paintComponent( )

It is a main method for painting
By default, it first paints the background
After that, it performs custom painting (drawing circle, rectangles etc.)

Graphic2D refers Graphic2D Class

Note: The Java 2D API enables you to easily perform the following tasks:

Draw lines, rectangles and any other geometric shape.
Fill those shapes with solid colors or gradients and textures.
Draw text with options for fine control over the font and rendering process.
Draw images, optionally applying filtering operations.
Apply operations such as compositing and transforming during any of the above rendering operations.

Example 2: Drawing and Filling Oval

import javax.swing.*;    
import java.awt.*;    

public class MyPanel extends JPanel {
    @Override
    public void paintComponent(Graphics g){    
        // clear the previous painting
        super.paintComponent(g);    
        Graphics2D g2 = (Graphics2D)g;    
        g2.setColor(Color.blue);    
        g2.drawOval(0, 0, 20,20);  
        g2.fillOval(50,50,20,20);    
    }
}

g2.drawOval(int x,int y,int height, int width);
This method will draw an oval at specified x and y position with given height and width.

g2.fillOval(int x,int y,int height, int width); This method will fill an oval at specified x and y position with given height and width.

Previous Next

Java Language

Java Language 2D Graphics in Java

Introduction

Example 1: Draw and Fill a Rectangle Using Java

Example 2: Drawing and Filling Oval