Difference Between Runnable and Thread in Java

1. Introduction

In Java, multithreading can be achieved in two main ways:

• By extending the Thread class

• By implementing the Runnable interface

Both are used to create threads, but they differ in design, flexibility, and usage.

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2. Thread Class

Explanation

• Thread is a class in Java.

• To create a thread, you extend this class and override the run() method.

• Java does not support multiple inheritance, so extending Thread limits flexibility.

Example

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

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

Explanation of Code

• MyThread extends Thread → Inheriting Thread class

• run() → Defines the task

• start() → Creates a new thread and internally calls run()

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3. Runnable Interface

Explanation

• Runnable is an interface.

• You implement it and pass the object to a Thread.

• Allows multiple inheritance (via interfaces) → more flexible design.

Example

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

public class RunnableExample {
    public static void main(String[] args) {
        MyRunnable r = new MyRunnable();
        Thread t = new Thread(r);
        t.start();
    }
}

Explanation of Code

• implements Runnable → Define task separately

• Pass object to Thread

• start() executes run()

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4. Key Differences Table

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5. Why Runnable is Preferred?

Explanation

• Java supports single inheritance only.

• If you extend Thread, you cannot extend any other class.

• Runnable separates:

  • Task (Runnable)

  • Thread (Thread class)

This leads to better design and maintainability.

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6. Real-Time Example

class Task implements Runnable {
    public void run() {
        System.out.println(Thread.currentThread().getName());
    }
}

public class Main {
    public static void main(String[] args) {
        Task task = new Task();

        Thread t1 = new Thread(task);
        Thread t2 = new Thread(task);

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

Explanation

• Same task shared by multiple threads

• Promotes resource sharing and efficiency

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7. Summary

• Thread → Simpler but less flexible

• Runnable → Flexible and widely used

• Runnable is recommended in real-world applications

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