Implements Runnable Vs Extends Thread In Java

Q- What are the difference between extends Thread and implements Runnable in java?

Extends Thread	Implements Runnable
We have to override run method	We must implement run method
Inheritance:   If extends thread than we can't extends another class because multiple inheritance not allowed in java	If we implements Runnable interface than we can extends another class.
Loosely-coupled:   By extends Thread class our class become tightly coupled.	By implements Runnable interface both Task and Executor become loosely coupled. Thread is separate form the job of Threads.
Our class become overheated by extends thread class due to additional methods in thread class. Means inheriting all the functions of the Thread class which we may do not need	No overhead on any method because Runnable interface has no other methods then run().
Maintanance of code not easy.	Maintanance of code is easy.
Functions overhead:   Thread class creates a unique object and get associated with that object.   So that more memory required.	Thread defined by implementing Runnable interface shares the same object.   Multiple threads share the same objects. So that less memory is used.
Reusability :   By extends Thread in class, its contains both thread and job specific behavior code. So that once thread completes its execution , it can't be restart again.	By implements Runnable interface, we can create a different Runnable class for a specific behavior of  job. It provides the freedom to reuse the specific behavior job when required.

Example: Create thread extends Thread class.

package com.shubh.thread.example;

/*Create thread by extending the Thread class */
class CreateThreadUsingThread extends Thread {
 public void run() {
  try {
   /* Print the running thread */
   System.out.println("Thread " + Thread.currentThread().getId() + " is running");
  } catch (Exception e) {
   /* Throwing an exception */
   System.out.println("Exception is caught");
  }
 }
}

// Main Class
public class MainClass {
 public static void main(String[] args) {
  for (int i = 0; i < 10; i++) {
   CreateThreadUsingThread object = new CreateThreadUsingThread();
   object.start();
  }
 }
}

Example: Create thread implements Runnable interface.

package com.shubh.thread.example;

/*Create thread by implementing the Runnable Interface*/
class CreateThreadUsingRunnable implements Runnable {
 public void run() {
  try {
   // Print running thread
   System.out.println("Thread " + Thread.currentThread().getId() + " is running");
  } catch (Exception e) {
   // Throwing an exception
   System.out.println("Exception is caught");
  }
 }
}

// Main Class
public class MainClassRunnableTest {
 public static void main(String[] args) {
  for (int i = 0; i < 10; i++) {
   Thread object = new Thread(new CreateThreadUsingRunnable());
   object.start();
  }
 }
}