java 8 Interview Questions | Theoretical

Java 8 Theoretical Questions :
Java 8 Features
what actual advantages does Java 8 bring
What enhancement s have been done to JDK in Java 8
What changes have been done to HashMap in Java 8
How lambda expression and functional interfaces are related
What is stream pipelining
What are functional interfaces
Can you create your own functional interface
What is method reference in java 8
What is Optional? Why and how can you use it
Why are default methods needed in the interface
What’s the difference between findFirst() and findAny()