Java 8 Interview Questions and Answers

Lambda expressions can only be applied to abstract method of functional interface.

Runnable has only one abstract method called run, so it can be used as below:

Thread t1=new Thread(

  ()->System.out.println("In Run method")

);

Here we are using Thread constructor which takes Runnable as parameter. As you can see we did not specify any function name here, as Runnable has only one abstract method, java will implicitly create anonymous Runnable and execute run method.

It will be as good as below code.

Thread t1=new Thread(new Runnable() { 

   @Override

   public void run() {

      System.out.println("In Run method");

   }

});