Repaint() Method in Java

The repaint method in java is accessible in java.applet.Applet class is a final method utilized at whatever point we need to call update technique alongside the call to paint method; the call to refresh method clears the ongoing window, plays out an update, and a short time later calls paint method.

Syntax for Repaint() Method

public void repaint()
public void repaint(long m)
public void repaint(int a, int b, int breadth, int length)
public void repaint(long m, int a, int b, int breadth, int length)

The above Syntaxes are the syntaxes of repaint() method in java. The repaint technique is a piece of the java.applet.Applet class, and it can't be overridden. Hence repaint method can be straightforwardly called from a class inheriting Applet or its subclasses.

Working of Repaint() Method

The repaint() method is present in the Applet class. we cannot override the repaint() method because it is a final method. At whatever point the repaint() method is to be utilized, it ought to be straightforwardly called from the Applet class's child classes. The repaint() method is liable for taking care of update to the paint() pattern of the applet. At the point when we believe that a part should repaint itself, we have to call the repaint() method.

In the event that we have made changes to the presence of a part but have not rolled out any improvements to its size, then, at that point, we can call the repaint() method to refresh the new appearance of the part on the graphical UI. The repaint() strategy is a nonconcurrent method for the applet class. At the point when a call to repaint strategy is made, it plays out a solicitation to eradicate and perform redraw of the part after a little defer in time.

At whatever point the repaint method is summoned from a component, a solicitation is shipped off the graphical UI, which imparts to the graphical UI to play out some activity at a future occurrence time. The entire thought behind the repaint technique is to stay away from the call to paint () method straightforwardly.

Example:

Here, we have an example program of AWT that draws ovals when the mouse is clicked. To start with, we override the paint() method and put down certain focuses for the oval. Then, at that point, in mousePressed(), we call the repaint() method that will call the paint() technique subsequent to calling the update() technique.

// program to show the implementation of the repaint() method in java
//  program to draw an ovel in the frame when the mouse is clicked in the frame using JFramei,e. swings
importjava.awt.*;
importjava.awt.event.*;
importjavax.swing.*;
importjava.util.*;
public class Demo extends JPanel implements MouseListener {
	private Vector v;
	public Demo() {
		v = new Vector();
		setBackground(Color.black);
		// adding mouse listener
		addMouseListener(this);
	}
	public static void main(String args[]) {
		JFrame f = new JFrame(); // creating an object to the Jframe class
		f.getContentPane().add(new Demo());
		f.setTitle(" JavaTpoint "); // giving title to the frame
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // setting the closing operation
		f.setLocationRelativeTo(null); // fixing the local relative as null
		f.setSize(400, 400); // fixing the size of the frame 
		f.setVisible(true); // fixing the visibility of the frame
	}
	public void paint(Graphics g) { // paint() method
		super.paint(g); // calling the paint method present in the super class or parent class
		g.setColor(Color.white); // fixing the outline colour of the ovel as white
		Enumeration e = v.elements(); // creating the object to the enumeration class
		while(e.hasMoreElements()) {
			Point point = (Point)(e.nextElement());
			g.drawOval(point.x-20, point.y-20, 40, 40);
		}
	}
	public void mousePressed(MouseEvent e) {
		v.add(e.getPoint());
		repaint(); // calling the repaint() method
	}
	// MouseListener method implementation
	public void mouseClicked(MouseEvent e) {}
	public void mouseEntered(MouseEvent e) {}
	public void mouseExited(MouseEvent e) {}
	public void mouseReleased(MouseEvent e) {}
}

Output:

The frame before the mouse is clicked in the frame.

The frame after the mouse is clicked in the frame.

The above model gives an unmistakable comprehension of the repaint() method and its capability. We ought to call the repaint() method when we need the applet's update and paint cycle to be conjured. The calling repaint() method plays out a prompt update to the look and presence of a component.

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