java8 features

Java 8 features

Below are new features that are introduced in Java 8 :

1. Lambda expression
2. Functional Interface
3. Default Methods and static methods
4. Predefined Functional interfaces (Predicate, Functional, Consumer, supplier, etc.,.)
5. Double colon operator(::), Method reference, constructor reference
6. Streams
7. Date and Time API
8. Optional class
9. nashorn JavaScript engine
10. StringJoiner
11. Collectors class etc.,.

Lambda expression::

• It is an anonymous function i.e., a lambda expression is Nameless, without return type, without modifiers.
• It brings the benefits of functional programming into Java.
• Lambda expression can implement an interface that contains a Single Abstract Method(SAM.)
• Click here for details

Functional Interface::

• Interface which contains SAM(Single Abstract Method) is called Functional Interface
• It also contains Any number of default methods and static methods
• In order to invoke lambda expression, we require a Functional Interface.

Default Methods:

• Until Java 1.7, Every method present inside the interface is always public and abstract
• In Java 1.8V, default methods and static methods are allowed
• In Java 1.9V, private methods are allowed

Static Methods:

• From Java 1.8, the interface can contain static methods.
• We should call static methods in the interface by using its interface name only.
• static methods in an interface are by default not available to implementation classes. So we have to call by using interface name only.