Java 8 New Features - Introduction

INTRODUCTION

Java 8 came up with a lot of enhancements. Features like Lambda Expression and Streams plays a major role on simplicity and maintainable code.

This post aims to provide the outline of Java 8 new features.

1. Lambda Expressions
2. Functional Interfaces
3. Method References
4. Streams
5. Interface Enhancements
6. Collection Enhancements
7. Date & Time API Enhancements

LAMBDA EXPRESSIONS

• Lambda expression enables functional programming in java which is not present till Java 8
• Simplifies the code and removes unwanted codes(boilerplate codes).
• @FunctionalInterface annotation helps to create our own Functional Interfaces. A functional interface can contain only one method. An example is a Runnable Interface.
• Syntax : argument(s) -> expression
• Lambda expression can be defined without argument, one argument or multiple arguments
• without argument

MyLambda myLambda = () -> System.out.println("Test"); myLambda.foo();

• one argument

(a) -> System.out.println(a);

• multiple argument

MyMath add = (a, b) -> a + b; System.out.println("Sum is: " + add.calc(8, 4));

FUNCTIONAL INTERFACES

• Functional Interfaces are the java interfaces which will contain only one method.
• In Java 8, new package java.util.function has been introduced.
• Main interfaces are:
• Function - assignment for any lambda expressions
• Predicate
• Consumer
• Supplier

METHOD REFERENCES

• Method reference help to access the public & non-static method of any class.
• Syntax : Class::method
• Example: mylist.forEach(System.out::println)

STREAMS

• Streams are functional style.
• Mainly process the list of elements of any type.
• In Java 8, new package java.util.stream has been introduced.
• Main classes & Interfaces are
• Stream
• Collector
• Collectors
• Streams are processed without or multiple intermediate operations (intermediate streams) and terminal operations (final output).
• Intermediate operations are lazy operations which mean it will accept the input and wait for processing till the terminal operation is encountered. Example operations are
• filter
• map
• mapToInt
• Terminal operations are
• sum
• average
• min
• max

INTERFACE ENHANCEMENTS

• Java 8 provides another interesting feature in the interface like having concrete methods in it.
• concrete methods in the interfaces are either static or default access modifier.

Example:

public interface Test {  void food();    default void speak() {    System.out.println("i can't speak :(");  }    default double average() {           return 20 / 5;  }    static void fly() {    System.out.println("i can't fly :(");  }    static int add() {    return 5 + 4;  }    static List<String> cities() {    return Arrays.asList("Chennai", "Mumbai", "Bangalore");  } }

Hope this post gives a brief introduction to Java 8 new features and enhancements.

Please share your thoughts in the comment box.

Happy Knowledge Sharing!!!