Lambda expressions for new features of JAVA8

Lambda expression

Simplifying the process of instantiating a functional interface (functional interface)

The benefits of lambda expressions

Simplifying the implementation of code

The syntax of a lambda expression

• A LAMBDA expression can have 0 or more parameters
• The type of the parameter can be either explicitly declared or inferred from the context. For example: (int a) the same as the (a) effect
• All parameters need to be enclosed in parentheses, and the parameters are separated by commas. For example: (a, b) or (int a, int b) or(String a, int b, float c)
• An empty parenthesis indicates that the parameter set is empty. For example:() -> 42
• When there is only one argument, and its type is inferred, parentheses () can be omitted. For example:a -> return a*a
• The body of a LAMBDA expression can contain 0 or more statements
• If the body of a LAMBDA expression has only one statement, the curly brace {} can be omitted. The return type of an anonymous function is consistent with the body expression
• If the body of a LAMBDA expression contains more than one statement, the expression must be enclosed in curly braces {} (forming a code block). The return type of the anonymous function is the same as the return type of the code block, or null if no return

Use of lambda expressions

1. Examples of lambda expressions for functional interfaces

Traditional implementations  Public void Runthread () {    new Thread (new  Runnable () {        publicvoid  Run () {            System.out.println ("run!" );        }    }). Start ();}

lambda expression Implementation  Public void Runthreaduselambda () {    new Thread ((), {        System.out.println("run!") );    }). Start ();}

2. Method Reference and Construction reference (method reference is another way to implement a functional interface)

= Arrays.aslist (new string[] {"Apple", "orange", "pear", System.out.println (v));

= Arrays.aslist (new string[] {"Apple", "orange", "Pear"}); Input.foreach (System.out::p rintln);

3.jdk8 for collection operations (introduction of Java.util.stream.Stream, default method + function interface as parameter +LAMBDA expression)

Traditional Implementation list<Integer> list = arrays.aslist (1,2,3,4,5,6,7);  for (Integer n:list) {    int x = n * N;    SYSTEM.OUT.PRINTLN (x);}

Stream implements list<Integer> list = arrays.aslist (1,2,3,4,5,6,7-x*x). ForEach (System.out:: PRINTLN);

Reference links

Http://blog.oneapm.com/apm-tech/226.html

Http://baike.baidu.com/item/Lambda%E8%A1%A8%E8%BE%BE%E5%BC%8F

Http://www.infoq.com/cn/articles/Java-se-8-lambda

Https://dzone.com/articles/why-we-need-Lambda-expressions

Lambda expressions for new features of JAVA8