Lambda expressions are introduced in Java 8. They help us to remove lot of bolier plate code for interface implementations using an inner class. In this blogpost, we will answer following questions: 1. What is a Functional Interface ? 2. What are Lambda Expressions and how to use them ? 3. Can an interface have default method implementations ? 4. Can a Functional Interface have more than one abstract method ? Create a java file and name it as "TestLambda". Copy paste the below code and run the program. Read the method signatures to get more understanding :