Multithreading In Java, PW Skills

Multithreading in Java is a process of executing multiple threads simultaneously. It improves the performance of an application as the utilisation of resources becomes more efficient.

Java is a popular programming language, and multithreading in Java is an important feature. Java supports multithreading, making it a favourite choice for developing various applications worldwide. Multithreading in Java is the process of executing multiple threads simultaneously. It improves the performance of an application as the utilization of resources becomes more efficient.

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Table of Contents

What are Threads in Java?

Threads are a lightweight sub-process that is also known as the smallest unit of processing. The threads in Java are independent units of the execution environment in which the Java applications run. Threads in Java are managed by the Java Virtual Machines (JVM) and Operating system.

Creating threads in Java is easy. You only need to extend the Thread class and override the run () method. Threads being independent are not affected if one thread stops working or creates an expectation. Multithreading is an important characteristic of threads because it helps to execute many threads at one time. Let us learn more about multithreading in Java in this article.

There are two types of threads in Java.

1. User thread: The user threads are created by the users to carry out specific tasks in Java. It can be created by extending the Java Thread class in the runnable interface.
Daemon thread: The daemon threads run in the background, which runs in the background to perform essential tasks such as garbage collection, etc.

Also, check: Python vs Java

What is Multithreading in Java?

Multithreading is a process that allows one or more threads to run concurrently. Threads are the lightweight, sub-process, smallest processing unit, which makes multitasking possible.

As we all know, many processes are running simultaneously on our computers, often known as multitasking. In a simple program, the process execution occurs sequentially, leading to resource wastage and starvation. With the help of multithreading, we can run many tasks in parallel at one time.

Working on Multithreading in Java

In Java, multithreading becomes possible with the help of the Thread class. With the help of the Java Thread class, we can create many lightweight processes and execute tasks in parallel. It makes our operating system more efficient.

Types of Multithreading in Java

Multithreading in Java can be achieved in two ways. Let us know the two major types of multithreading in Java.

1. Thread-based Multithreading in Java

The thread-based multithreading in Java is one of the most favourable ways of implementing multithreading in Java. You can create a Thread class and override it using the run() method for the parallel process you want to execute.

Multithreading in Java

class MyThread extends Thread {

public void run() {

// Code to be executed in the thread

System.out.println(“Thread is running”);

}

public class Main {

public static void main(String args[]) {

MyThread myThread = new MyThread();

myThread.start(); // This method starts the execution of the thread

}

2. Runnable Interface-Based Multithreading in Java

This is the second way of implementing multithreading in Java. Here, we do not need to extend the Thread class. Instead, we do not need to extend the Thread class; instead, we just need to implement the Runnable interface, which distinguishes the identity of the thread from its behaviour. Let us check out an example below to understand the implementation.

Multithreading in Java: Runnable interface-based

class MyRunnable implements Runnable {

public void run() {

// Code to be executed in the thread

System.out.println(“Thread is running”);

}

public class Main {

public static void main(String args[]) {

Thread myThread = new Thread(new MyRunnable());

myThread.start();

}

Also check: Java coding basics

Java Threads Methods

Multithreading in Java: Important Methods
S.No.	Method	Description
1	start()	Used to start the execution of the thread.
2	run()	Used to perform an action for a thread.
3	sleep()	Sleeps a thread for the specified amount of time.
4	currentThread()	Returns a reference to the currently executing thread object.
5	join()	Waits for a thread to die.
6	getPriority()	Returns the priority of the thread.
7	setPriority()	Changes the priority of the thread.
8	getName()	Returns the name of the thread.
9	setName()	Changes the name of the thread.
10	getId()	Returns the ID of the thread.
11	isAlive()	Tests if the thread is alive.
12	yield()	Causes the currently executing thread object to pause and allows other threads to execute temporarily.
13	suspend()	Suspends the thread.
14	resume()	Resumes the suspended thread.
15	stop()	Stops the thread.
16	destroy()	Destroys the thread group and all of its subgroups.
17	isDaemon()	Tests if the thread is a daemon thread.
18	setDaemon()	Marks the thread as a daemon or user thread.
19	interrupt()	Interrupts the thread.
20	isInterrupted()	Tests whether the thread has been interrupted.
21	interrupted()	Tests whether the current thread has been interrupted.
22	activeCount()	Returns the number of active threads in the current thread’s thread group.
23	checkAccess()	Determines if the currently running thread has permission to modify the thread.
24	holdLock()	Returns true if and only if the current thread holds the monitor lock on the specified object.
25	dumpStack()	Prints a stack trace of the current thread to the standard error stream.
26	getStackTrace()	Returns an array of stack trace elements representing the stack dump of the thread.
27	enumerate()	Copies every active thread’s thread group and its subgroup into the specified array.
28	getState()	Returns the state of the thread.
29	getThreadGroup()	Returns the thread group to which this thread belongs.
30	toString()	Returns a string representation of this thread, including the thread’s name, priority, and thread group.
31	notify()	Gives notification for only one thread waiting for a particular object.
32	notifyAll()	Gives notification to all waiting threads of a particular object.
33	setContextClassLoader()	Sets the context ClassLoader for the thread.
34	getContextClassLoader()	Returns the context ClassLoader for the thread.
35	getDefaultUncaughtExceptionHandler()	Returns the default handler invoked when a thread abruptly terminates due to an uncaught exception.
36	setDefaultUncaughtExceptionHandler()	Sets the default handler invoked when a thread abruptly terminates due to an uncaught exception.

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Multithreading in Java FAQs

Q1. What is multithreading in Java?

Ans: Multithreading is a process that allows one or more threads to run concurrently.

Q2. How do you implement multithreading in Java?

Ans: Creating threads in Java is easy. You only need to extend the Thread class and override the run() method. However, there are more methods given in the article.

Q3. How many types of multithreading are there in Java?

Ans: There are mainly two types of multithreading in Java, Thread based multithreading and Runnable interface-based multithreading in Java.