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So far you have come across threads that are based on a class with a specific name, a class which has either extended the Thread class or has implemented the Runnable interface. Some of you might be surprised to know that we can even create threads that are based on anonymous classes, i.e. classes with no name. For those of you, who are not completely aware of an anonymous class in Java, we would suggest you to please click here to know more about it.

For those who are aware of anonymous classes, let's go on with this article.

How to create an anonymous thread -


We can create an anonymous thread in two ways -
• By creating an anonymous class, which has extended the Thread class and has overridden its run() method, or,
• By creating an anonymous class, which has implemented the Runnable interface and also its run() method.

Note: We can create a thread, based on the object of an anonymous class i.e. a class with no name which has either extended the Thread class or has implemented the Runnable interface. Hence, a thread based on the object of such anonymous class is called an Anonymous Thread.






• Creating an anonymous thread by extending the Thread class.



• In the upcoming program, we are going to create an object of an anonymous class, which has extended the Thread class and has overridden its run() method.
• Next, we are going to pass an object of this anonymous class to the reference of Thread class, which is fine because a Thread reference can point to the object of its subclasses(in this case, an anonymous class).



//An anonymous thread by extending the Thread class
 
class A 
{
public static void main(String... ar)
{

Thread t= new Thread(){ 	//Creating an object of Anonymous class which extends Thread class and passing this object to the reference of Thread class.
	public void run()	//Anonymous class overriding run() method of Thread class
	{
	setName("Anonymous Thread");	
	System.out.println("Name of the other thread - " + getName());
	for(int i=0;i<3;i++)
	{
		System.out.println(getName() + " " + i);
	}

	}
	};				//Anonymous class ends here
	
//Starting anonymous thread
t.start();

//Gets the name of main thead
System.out.println("Name of main thread - "+ Thread.currentThread().getName()); 
}
}

Output is - :

Name of main thread - main
Name of the other thread - Anonymous Thread 
Anonymous Thread 0
Anonymous Thread 1
Anonymous Thread 2




Program Analysis



• A new thread is created based on an object of an anonymous class, which has extended the Thread class.
• A method call t.start() starts the execution of the anonymous thread by calling its run() method.
• In run(), the method setName() is called to set the name of the newly created anonymous thread to - Anonymous Thread.
• Next, the anonymous thread enters the for-loop and iterate through it 3 times, printing its name.
• While, the getName() method is called on the main thread, to display its name on the console.





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• Creating an anonymous thread by implementing the Runnable interface class.



• In the next program, we have going to create an object of an anonymous class, which has implemented the Runnable interface and its run() method.
• Next, we are going to pass the object to of this anonymous class to the constructor of Thread class, because the constructor of Thread class takes takes a Runnable interface type and the anonymous class has also become a Runnable type.



 //An anonymous thread by implementing the Runnable interface

class A 
{
public static void main(String... ar)
{

Runnable r = new Runnable(){	 //Creating an object of Anonymous class that implemented Runnable interface
	public void run()	 //Anonymous class implementing run() method of Runnable class
	{
	Thread t= Thread.currentThread();
	t.setName("Anonymous Thread");	
	System.out.println("Name of the other thread - " + t.getName());
	for(int i=0;i<3;i++)
	{
		System.out.println(t.getName() + " " + i);
	}

	}
	};

Thread t= new Thread(r);  //Passing the object of anonymous class to the constructor of Thread
t.start();		  //Starting the anonymous thread

//Gets the name of main thead
System.out.println("Name of main thread - "+ Thread.currentThread().getName()); 
}
}





Output is -:




Name of main thread - main
Anonymous Thread 0
Anonymous Thread 1
Anonymous Thread 2


In order to keep things simple for the readers, we have kept both programs i.e.
• an anyonymous thread by extending the Thread class
• anonymous thread by implementing the Runnable interface
quite similar.




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