Java Thread start()

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

In this guide, you will learn about the Thread start() method in Java programming and how to use it with an example.

1. Thread start() Method Overview

Definition:

The Thread.start() method is used to start the execution of a new thread. The Java Virtual Machine calls the run() method of this thread.

Syntax:

public void start()

Parameters:

None.

Key Points:

- This method initiates a call to the run() method of the Thread class.

- Once the start() method is called, the Java runtime takes over and the JVM decides when the thread will actually run.

- Invoking the start() method on a thread that's already started will lead to an IllegalThreadStateException.

- It's essential to differentiate between start() and run(). Directly calling run() will execute the method in the current thread rather than starting a new thread.

2. Thread start() Method Example

public class ThreadStartExample {
    public static void main(String[] args) {
        // Create a new thread
        Thread newThread = new Thread(() -> {
            for(int i = 0; i < 5; i++) {
                System.out.println("Inside new thread");
            }
        });

        // Start the new thread
        newThread.start();

        for(int i = 0; i < 5; i++) {
            System.out.println("Inside main thread");
        }
    }
}

Output:

Inside main thread
Inside new thread
Inside main thread
Inside new thread
Inside main thread
Inside new thread
Inside main thread
Inside new thread
Inside new thread

Explanation:

In the example, we create a new thread and use the Thread.start() method to start its execution. The new thread prints "Inside new thread" 5 times, and the main thread prints "Inside main thread" 5 times. The exact order of the outputs might vary because the execution order of threads is not guaranteed. Therefore, different runs may produce slightly different interleaved outputs.

My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:

Build REST APIs with Spring Boot 4, Spring Security 7, and JWT

🆕 High-Demand 80–90% OFF

[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25

🆕 High-Demand 80–90% OFF

ChatGPT + Generative AI + Prompt Engineering for Beginners

🚀 Trending Now 80–90% OFF

Spring 7 and Spring Boot 4 for Beginners (Includes 8 Projects)

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Real-Time REST APIs with Spring Boot - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Building Microservices with Spring Boot and Spring Cloud

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Java Full-Stack Developer Course with Spring Boot and React JS

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Build 5 Spring Boot Projects with Java: Line-by-Line Coding

🌟 Top Rated 80–90% OFF

Testing Spring Boot Application with JUnit and Mockito

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot Thymeleaf Real-Time Web Application - Blog App

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Master Spring Data JPA with Hibernate

🔥 Bestseller 80–90% OFF
Available in Udemy for Business

Spring Boot + Apache Kafka Course - The Practical Guide

🎓 Student Favorite 80–90% OFF
Available in Udemy for Business

Java Testing: Mastering JUnit 5 Framework

🆕 New 80–90% OFF

Reactive Programming in Java: Spring WebFlux and Testing

🌟 Top Rated 80–90% OFF

Spring Boot + RabbitMQ Course - The Practical Guide

🌟 Top Rated 80–90% OFF
Available in Udemy for Business

Functional Programming in Java (Includes Java Collections)

🎓 Student Favorite 80–90% OFF

ChatGPT for Java Developers: Boost Your Productivity with AI

🚀 Trending Now 80–90% OFF