Difference Between Thread and Runnable in Java

There are two ways to create a new thread of execution. One is to declare a class to be a subclass of the Thread class. This subclass should override the run method of the Thread class. An instance of the subclass can then be allocated and started.

The other way to create a thread is to declare a class that implements the Runnable interface. That class then implements the run method. An instance of the class can then be allocated, passed as an argument when creating Thread, and started.

Every thread has a name for identification purposes. More than one thread may have the same name. If a name is not specified when a thread is created, a new name is generated for it.

What is a thread?

A thread is a lightweight process and a basic unit of CPU utilization that consists of a program counter, a stack, and a set of registers.

Example

The following is an example of thread in Java:

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

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

The output of the above Java program is :

Thread is running

What is runnable?

A Runnable is a functional interface that enables the compiled code of the class to run as a separate thread.

Example

The following is an example of runnable in Java:

public class RunnableExample implements Runnable {
   public void run() {
      System.out.println("Thread is running for Runnable Implementation");
   }

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

The output of the above Java program is :

Thread is running for Runnable Implementation

Difference between Thread and Runnable

The following table provides differences between Thread and Runnable: