Multithreading example in Java

Any application can have multiple processes (instances). Each of this process can be assigned either as a single thread or multiple threads.

What is Single Thread?

Single threaded processes contain the execution of instructions in a single sequence. In other words, one command is processes at a time.

Example:

	public class SingleThread{
	public static void main(String[] args) {
	System.out.println("Single Thread");
	}
	}

view raw singleThreadExample.java hosted with ❤ by GitHub

What is Multithreading in Java?

The opposite of single threaded processes are multithreaded processes. These processes allow the execution of multiple parts of a program at the same time.

This is an animated example for a deep understanding:

Its source code:

	import java.awt.Color;
	import java.awt.Point;
	import java.awt.event.ActionEvent;
	import java.awt.event.ActionListener;
	import javax.swing.BorderFactory;
	import javax.swing.JButton;
	import javax.swing.JFrame;
	import javax.swing.JPanel;
	public class MultithreadingExample {
	public static void main(String[] args) {
	JFrame window =new JFrame ("Processus");
	window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	window.setSize(500,500);
	window.setResizable(false);
	JPanel pan = new JPanel ();
	pan.setBackground(Color.yellow);
	pan.setLayout(null);
	pan.setBorder(BorderFactory.createLineBorder(Color.black));
	window.setContentPane(pan);
	JButton sqr1 = new JButton ();
	JButton sqr2 = new JButton ();
	JButton sqr3 = new JButton () ;
	JButton btn1 = new JButton ("Task 1") ;
	btn1.setBounds(30,400,100,50);
	pan.add(btn1);
	JButton btn2 = new JButton ("Task 2") ;
	btn2.setBounds(130,400,100,50);
	pan.add(btn2);
	JButton btn3 = new JButton ("Task 3") ;
	btn3.setBounds(230,400,100,50);
	pan.add(btn3);
	JButton btn4 = new JButton ("All Tasks") ;
	btn4.setBounds(330,400,150,50);
	pan.add(btn4);
	sqr1.setBounds(40,300,50,50);
	sqr1.setBackground(Color.black);
	sqr1.setEnabled(false);
	sqr2.setBounds(390,300,50,50);
	sqr2.setBackground(Color.black);
	sqr2.setEnabled(false);
	sqr3.setBounds(40,40,100,50);
	sqr3.setBackground(Color.black);
	sqr3.setEnabled(false);
	pan.add(sqr1);
	pan.add(sqr2);
	pan.add(sqr3);
	window.setVisible(true);
	btn1.addActionListener(new ActionListener(){
	@Override
	public void actionPerformed(ActionEvent e) {
	btn1.setEnabled(false);
	Thread thread = new Thread() {
	@Override
	public void run() {
	Point point = sqr1.getLocation();
	Point point2 = sqr2.getLocation();
	while (point.x!=201) {
	sqr1.setLocation(point.x,point.y);
	point.x++ ;
	try {
	Thread.sleep(20);
	} catch (InterruptedException ex) {}
	}
	while(sqr2.getLocation().x != 250){/* wait */}
	point = sqr1.getLocation();
	point2 = sqr2.getLocation();
	while (point.y!=90) {
	sqr2.setLocation(point2.x,point2.y);
	sqr1.setLocation(point.x,point.y);
	point.y-- ;
	point2.y-- ;
	try {
	Thread.sleep(20);
	} catch (InterruptedException ex) {}
	}
	}
	};
	thread.start();
	}
	});
	btn2.addActionListener(new ActionListener(){
	@Override
	public void actionPerformed(ActionEvent e) {
	btn2.setEnabled(false);
	Thread thread = new Thread() {
	Point point = sqr2.getLocation();
	Point point1 = sqr1.getLocation();
	@Override
	public void run() {
	while (point.x!=249) {
	sqr2.setLocation(point.x,point.y);
	point.x-- ;
	try {
	Thread.sleep(20);
	} catch (InterruptedException ex) {}
	}
	while(sqr1.getLocation().x != sqr2.getLocation().x -50){/* wait */}
	point = sqr2.getLocation();
	point1 = sqr1.getLocation();
	while (point.y!=90) {
	sqr2.setLocation(point.x,point.y);
	sqr1.setLocation(point1.x,point1.y);
	point.y-- ;
	point1.y-- ;
	try {
	Thread.sleep(20);
	} catch (InterruptedException ex) {}
	}
	}
	};
	thread.start();
	}
	});
	btn3.addActionListener(new ActionListener(){
	@Override
	public void actionPerformed(ActionEvent e) {
	btn3.setEnabled(false);
	Thread thread = new Thread() {
	Point p3 = sqr3.getLocation();
	Point p1 = sqr1.getLocation();
	Point p2 = sqr2.getLocation();
	@Override
	public void run() {
	while (p3.x!=202) {
	sqr3.setLocation(p3.x,40);
	p3.x++ ;
	try {
	Thread.sleep(20);
	} catch (InterruptedException ex) {}
	}
	while(sqr1.getLocation().y != 91){System.out.println();/* wait */}
	p3 = sqr3.getLocation();
	p1 = sqr1.getLocation();
	p2 = sqr2.getLocation();
	while (p3.x!=500) {
	sqr3.setLocation(p3.x,p3.y);
	sqr1.setLocation(p1.x,p1.y);
	sqr2.setLocation(p2.x,p2.y);
	p3.x++ ;
	p1.x++ ;
	p2.x++ ;
	try {
	Thread.sleep(20);
	} catch (InterruptedException ex) {}
	}
	}
	};
	thread.start();
	}
	});
	btn4.addActionListener(new ActionListener() {
	@Override
	public void actionPerformed(ActionEvent e) {
	btn4.setEnabled(false);
	btn1.doClick();
	btn2.doClick();
	btn3.doClick();
	}
	});
	}
	}

view raw multithreadingExample.java hosted with ❤ by GitHub

Advantages of Multithreaded Processes:

• Enhanced performance by decreased development time
• Simplified and streamlined program coding
• Improvised GUI responsiveness
• Simultaneous and parallelized occurrence of tasks
• Better use of cache storage by utilization of resources
• Decreased cost of maintenance
• Better use of CPU resource

Disadvantages of Multithreaded Processes:

• Complex debugging and testing processes
• Overhead switching of context
• Increased potential for deadlock occurrence
• Increased difficulty level in writing a program
• Unpredictable results