Thread in Java

What is thread in Java?

A thread in Java, is a separate path of execution within a Java program. It is a lightweight version of a process.

We use threads to improve the performance of a program by allowing multiple tasks to run or execute concurrently. For example, a web browser can use multiple threads to download images, render pages, and handle user input.

There are different ways to create thread in Java but basically, there are two ways to create thread in Java.

You can click on create thread in Java to learn more detail about it.

Once we have created a thread, we can start it by calling the start() method. The start() method will cause the thread to run its run() method. The run() method is where we put the code that we want the thread to execute.

Following is an example of how to create a thread in Java:

class MyThread extends Thread {

    public void run() {
        System.out.println("Hello, world!");

    public static void main(String[] args) {
        MyThread thread = new MyThread();

This code will create a new thread and start it. The thread will print the message “Hello, world!” to the console.

Types of threads in Java

There are two types of threads in Java:

  • User threads and
  • Daemon threads.

User threads are the ones that we create. Daemon threads are used to perform background tasks, such as garbage collection.

When a Java program terminates, all of the user threads are terminated as well. However, daemon threads continue to run until they are finished with their tasks.

Threads can be synchronized to ensure that only one thread can access a shared resource at a time. This is important to prevent race conditions, which can occur when multiple threads try to access the same resource at the same time.

Benefits of using threads in Java

  • Improved performance: Threads can improve the performance of an application by allowing it to do multiple things at the same time.
  • Increased responsiveness: Threads can make an application more responsive by allowing it to respond to user input while other tasks are still running in the background.
  • Reduced resource usage: Threads can help to reduce resource usage by allowing multiple tasks to share the same resources.

Challenges of using threads in Java

  • Deadlocks: Deadlocks can occur when two or more threads are waiting for each other to release a resource.
  • Race conditions: Race conditions can occur when the outcome of a program depends on the order in which threads access a shared resource.


How do I start a thread in Java?

Once you have created a thread, you must start it by calling the start() method on the thread object.

How do I stop a thread in Java?

There are two ways to stop a thread in Java:
Call the stop() method on the thread object: This is not recommended, as it can cause the thread to leave its resources in an inconsistent state.
Call the interrupt() method on the thread object: This is the preferred way to stop a thread, as it allows the thread to clean up its resources before exiting.

What is thread synchronization?

Thread synchronization is the process of ensuring that multiple threads can safely access shared resources without causing data corruption.
There are a number of ways to synchronize threads in Java, such as using locks, semaphores, and wait-free algorithms.

What are some best practices for using threads in Java?

The best practices for using threads in Java are:
Use the Runnable interface to create threads instead of extending the Thread class.

Use locks or other synchronization mechanisms to protect shared resources from concurrent access.

Avoid using the stop() method to stop threads. Instead, use the interrupt() method.

Be careful of deadlocks.