Introduction to Threads in Java

What are Threads in Java?

A thread in Java is the smallest unit of a process that can execute independently. Threads allow a program to perform multiple tasks simultaneously, making applications more responsive and efficient. The use of multithreading is especially important in modern applications that require concurrency, such as real-time systems, games, or web servers.

Java provides built-in support for threads via the java.lang.Thread class and the Runnable interface.

Why Use Threads in Java?

• Improves performance through parallel execution.

• Enhances responsiveness in applications (e.g., GUIs).

• Utilizes CPU resources more efficiently.

• Simplifies asynchronous and background tasks.

Creating Threads in Java

There are two common ways to create threads in Java:

1. Extending the Thread Class

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

    public static void main(String[] args) {
        MyThread t1 = new MyThread();
        t1.start();
    }
}

2. Implementing the Runnable Interface

class MyRunnable implements Runnable {
    public void run() {
        System.out.println("Runnable thread is running...");
    }

    public static void main(String[] args) {
        Thread t1 = new Thread(new MyRunnable());
        t1.start();
    }
}

Thread Lifecycle in Java

A thread in Java goes through the following states:

1. New → Created but not started.

2. Runnable → Ready to run.

3. Running → Actively executing.

4. Waiting/Timed Waiting → Waiting for another thread or event.

5. Terminated → Completed execution.

Example of Multiple Threads

class MultiThreadExample extends Thread {
    public void run() {
        System.out.println(Thread.currentThread().getName() + " is running");
    }

    public static void main(String[] args) {
        MultiThreadExample t1 = new MultiThreadExample();
        MultiThreadExample t2 = new MultiThreadExample();

        t1.start();
        t2.start();
    }
}

Output:

Thread-0 is running
Thread-1 is running

Advantages of Using Threads

• ✔ Better resource utilization

• ✔ Faster execution through parallelism

• ✔ Simplifies complex asynchronous tasks

Disadvantages

• Increased complexity in debugging

• Risk of deadlocks and race conditions

• Higher memory consumption with too many threads

Final Thoughts

Threads are a core feature of Java’s concurrency model, enabling developers to build responsive and high-performance applications. Understanding thread creation, lifecycle, and best practices is crucial for writing scalable and efficient Java programs.