37. Explain different ways of creating a thread

Threads can be used by either :

• Extending the Thread class

• Implementing the Runnable interface.

class Counter extends Thread {

// method where the thread execution will start

public void run() {

// logic to execute in a thread

}

// let’s see how to start the threads

public static void main(String[] args) {

Thread t1 = new Counter();

Thread t2 = new Counter();

t1.start(); // start the first thread. This calls the run() method

t2.start(); // this starts the 2nd thread. This calls the run() method

}

}

class Counter extends Base implements Runnable {

// method where the thread execution will start

public void run() {

// logic to execute in a thread

}

// let us see how to start the threads

public static void main(String[] args) {

Thread t1 = new Thread(new Counter());

Thread t2 = new Thread(new Counter());

t1.start(); // start the first thread. This calls the run() method

t2.start(); // this starts the 2nd thread. This calls the run() method

}

}

The runnable interface is preferred, as it does not require your object to inherit a thread because when you need multiple inheritance, only interfaces can help you. In the above example we had to extend the Base class so implementing runnable interface is an obvious choice. Also note how the threads are started in each of the different cases as shown in the code sample.