Java 8 Features

Question 1

1.Can you tell me the Java 8 Features

Answer 1

Lambda Expressions, Functional Interface, Stream API,
Default Methods, Optional Class, New Date and Time APi, Nashorn javascript engine, parallel array sorting, collectors, String Joiner Class

Question 2

2.What are the Functions available in Functional Interface?

Answer 2

Predicate, Function, Consumer , Supplier
BiPredicate, BiFunction, BiConsumer

Question 3

What is an Interface?

Answer 3

An interface or a protocol type that acts as a abstraction class

1.An interface have many number of abstract method
A class which implements the interface must give the implementations of that method
2. In interface explicitly we don’t want to mention the public abstract , by default abstract method in interface is public.

Question 4

5.What is a Functional Interface?

Answer 4

A Functional interface is a interface , where it will be having only one abstract method and we can have many default and static methods.

1.We can use @FunctionalInterface Annotation to make sure that the compiler knows it.

Question 5

6.Can we have default and static methods in Functional Interface?

Answer 5

Yes we can have default and static
methods in a Functional interface.

Question 6

7.What is Marker interface?

Answer 6

An interface with no members or methods is known as Marker Interface.

Question 7

Why Functional Interface have only one abstract method?

Answer 7

This Design servers several purposes , like Lambda expressions and method references.

1.Simplicity and clarity
2. Avoid Ambiquity

Enabling Lambda Expressions and Method References:

Question 8

What the pre-defined functional Interface before Java 8?

Answer 8

1.Runnable
public abstract void run();
2.Callable
3.Comparator
int compare (T o1, T o2)
4.ActionListener Interface
public void actionPerfomed (ActionEvent e);