How to display colours in a frame using Java

Problem Description

How to display colours in a frame?

Solution

Following example displays how to a display all the colors in a frame using setRGB method of image class.

import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import javax.swing.JComponent;
import javax.swing.JFrame;

public class Main extends JComponent {
   BufferedImage image;
   public void initialize() {
      int width = getSize().width;
      int height = getSize().height;
      int[] data = new int[width * height];
      int index = 0;
      
      for (int i = 0; i < height; i++) {
         int red = (i * 255) / (height - 1);
         for (int j = 0; j < width; j++) {
            int green = (j * 255) / (width - 1);
            int blue = 128;
            data[index++] = (red<<16) | (green<<8) | blue;
         }
      }
      image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
      image.setRGB(0, 0, width, height, data, 0, width);
   }
   public void paint(Graphics g) {
      if (image == null)
      initialize();
      g.drawImage(image, 0, 0, this);
   }
   public static void main(String[] args) {
      JFrame f = new JFrame("Display Colours");
      f.getContentPane().add(new Main());
      f.setSize(300, 300);
      f.setLocation(100, 100);
      f.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
         }
      });
      f.setVisible(true);
   }
}

Result

The above code sample will produce the following result.

Displays all the colours in a frame.

The following is an example to display colours in a frame.

import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class Panel { 
   public static void main(String[] args) { 
      SwingUtilities.invokeLater(new Runnable() { 
         public void run() { 
            displayJFrame();
         } 
      }); 
   } 
   static void displayJFrame() { 
      JFrame frame = new JFrame("Tutorialspoint");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setBackground(Color.red);
      frame.setPreferredSize(new Dimension(400, 300));
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
}