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Java Lambda expression method reference and constructor reference example analysis, in view of this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

A little bit of eye contact

If the code block of a Lambda expression has only one code, you can also use method references and constructor references in the code block to make the Lambda expression more concise.

Kinds

Example

Description

Corresponding Lambda expression

Reference class method

Class name:: class method

All the parameters of the implemented method in the functional interface are passed to this kind of method as parameters.

The name of the class (a dint bpcr...) Class method (aformab,...)

An instance method that references a specific object

Specific object:: instance method

All the parameters of the implemented method in the functional interface are passed to the method as parameters.

(a) b,...)-> specific object. Example method (aformab,...)

An instance method that refers to a class of objects

Class name:: instance method

The first parameter of the implemented method in the functional interface is the caller, and all the subsequent parameters are passed to the method as parameters.

(a) b,...)-> a. Instance method (b,...)

Reference constructor

Class name:: new

All parameters of the implemented method in the functional interface are passed to the constructor as parameters.

(a _ dint b,...)-> new class name (a _ r b,...)

Second actual combat

1 code

Import javax.swing.*;@FunctionalInterfaceinterface Converter {Integer convert (String from);} @ FunctionalInterfaceinterface MyTest {String test (String a, int b, int c);} @ FunctionalInterfaceinterface YourTest {JFrame win (String title);} public class MethodRefer {public static void main (String [] args) {/ / the following code uses Lambda expressions to create Converter objects / / Converter converter1 = from-> Integer.valueOf (from); / / method references instead of Lambda expressions: reference class methods. / / all the parameters of the implemented method in the functional interface are passed to this kind of method as parameters. Converter converter1 = Integer::valueOf; Integer val = converter1.convert ("99"); System.out.println (val); / / output integer 99 / / the following code uses the Lambda expression to create a Converter object / / Converter converter2 = from-> "fkit.org" .indexOf (from); / / method reference instead of Lambda expression: an instance method that references a specific object. / / all the parameters of the implemented method in the functional interface are passed to the method as parameters. Converter converter2 = "fkit.org":: indexOf; Integer value = converter2.convert ("it"); System.out.println (value); / / output 2 / / the following code uses the Lambda expression to create a MyTest object / / MyTest mt = (a, b, c)-> a.substring (b, c); / / method reference instead of Lambda expression: an instance method that references an object of some kind. / / the first parameter of the implemented method in the functional interface is used as the caller, and / / all the subsequent parameters are passed to the method as parameters. MyTest mt = String::substring; String str = mt.test ("Java I Love you", 2,9); System.out.println (str); / / output: the following code uses the Lambda expression to create the YourTest object / / YourTest yt = (String a)-> new JFrame (a); / / the constructor reference replaces the Lambda expression. / / all the parameters of the implemented method in the functional interface are passed to the constructor as parameters. YourTest yt = JFrame::new; JFrame jf = yt.win (my window); System.out.println (jf);}}

2 run

992va I Lojavax.swing.JFrame [frame0,0,0,0x0,invalid,hidden,layout=java.awt.BorderLayout,title= my window, resizable,normal,defaultCloseOperation=HIDE_ON_CLOSE,rootPane=javax.swing.JRootPane [, 0JJJRootPaneBook Layout.javax.swing.JRootPaneEncoding RootLayoutDivision], rootPaneCheckingEnabled=true]

This is the answer to the sample analysis questions about the method reference of Java Lambda expression and the constructor reference. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel for more related knowledge.

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