Definition

A thread in Java is a lightweight process that can run concurrently within a Java program. Java supports multithreading, where multiple threads run independently and can communicate with each other, making it possible to handle multiple tasks within a single program.

How to Create a Thread

In Java, there are two primary ways to create a thread:

  • By extending the Thread class
  • By implementing the Runnable interface

Example:

class MyThread extends Thread {
    @Override
    public void run() {
        System.out.println("Thread is running using the Thread class.");
    }

    public static void main(String[] args) {
        MyThread thread = new MyThread();
        thread.start();  // Starts the thread
    }
}

Output:

Thread is running using the Thread class.

Example:

class MyRunnable implements Runnable {
    @Override
    public void run() {
        System.out.println("Thread is running using the Runnable interface.");
    }

    public static void main(String[] args) {
        MyRunnable myRunnable = new MyRunnable();
        Thread thread = new Thread(myRunnable);
        thread.start();  // Starts the thread
    }
}

Output:

Thread is running using the Runnable interface.

Features of Threads in Java

  • Multiple threads can execute independently.
  • The JVM can switch between threads efficiently.
  • Java provides mechanisms (such as synchronized keyword) to control access to resources across threads.
  • Threads have specific states, like NEW, RUNNABLE, BLOCKED, WAITING, TIMED_WAITING, and TERMINATED.
  • Threads can have priorities that influence the order of execution.
  • Threads can be set as daemon threads, which means they run in the background.

Advantages of Using Threads

  • Threads enable better CPU utilization by allowing multiple tasks to be executed simultaneously, especially on multi-core systems.
  • In GUI applications, threads allow time-consuming tasks (like network requests) to run in the background, keeping the UI responsive.
  • Multithreaded programs can sometimes simplify complex applications by dividing tasks into separate threads.
  • Threads within the same process can share resources more efficiently than separate processes can, because they share the same memory space.