Lambda expression: an article takes you through

One ,JDK8 introduce Lambda expression

JDk1.8 in the future Interface can There are common ways , It's not just abstract methods , The method is default Embellished , And this method , His implementation subclasses can call this method .

Define common methods in the interface , It is generally used to modify the shortcomings of the previous version . Developers can hardly use .

dafault Keyword represents a common method in an interface , Don't omit .

 

Two , Functional interface ： An interface has and has only one abstract method , It's a functional interface .

Use @FunctionalInterface To check whether it is a functional interface , There can only be one , No more , Not without it

1, Through anonymous inner classes , To implement functional interfaces

 

 

 2,Lambda expression , To implement the interface

 

3、 ... and ,lambda expression

 Lambda Expressions are based on functions and interfaces , If there are multiple interfaces or no interfaces , You won't find the abstract methods in the interface one by one .Lambda The expression will become error prone .

It is the implementation that only retains the parameters and body of the method .

Lambda Four forms of expressions ：

1, No return value , No parameter

2, No return value, parameter

 

3, With return value and no parameter

4, No return value no parameter

 

Four ,Lambda Features of expressions ：

1, If the implementation of a method has only one line of code , It can be omitted {}

 2, If method has only one parameter , Then brackets can be omitted

 

3, You can omit the types of expression parameters （ Or omit it all , Or don't omit it all ）

 

4, If the method body has a return value and the method body has only one line , It can be omitted {},return