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Definition of anonymous functionlambda parameter_list: expressionTwo: ternary expression Result returned when the condition is true if the condition determines the result returned when else condition is falseThree: map map(func(arg1, arg2...), list1_arg1, list2_arg2)， Perform the previous functions (mathematical mapping) on the list e ...

How to calculate the distance between two points specified by longitude and latitude? For clarity, I want the distance in kilometers; these points use the WGS84 system, and I want to know the relative accuracy of the available methods. #1st floor This is a simple PHP function that gives a very reasonable approximation (error range is ...

When type parameters are unknown at compile time, but are acquired dynamically at run time, what is the best way to call generic methods? Consider the following example code - inside the Example() method, what is the simplest way to call genericmethod < T > () using the Type stored in the myType variable? public class Sample { p ...

When we read the JDK reflection package source code, we will encounter the isSynthetic() method. One of its implementations is Modifier.isSynthetic(getModifiers()), and the principle of other methods is the same. Modifier is a special class for defining modifiers, among which static final int synchronous = 0x00001000 is one of the modifiers.I t ...

I. Basic Introduction Lambda Lambda is a new feature introduced by java 8. A lambda expression is an anonymous function. It provides a Simpler Syntax and cooperation mode, which enables us to replace the functional interface by expression. Lambda expressions can be used to simplify the creation of anonymous inner classes. Functional interfa ...

Preface In recent internship, I saw some codes of my predecessors in the company, and found that there are many places worth learning. One part of them is to use Stream stream operation for collection, which is very beautiful and convenient. So learn some Stream streams and record them here. What is Stream Stream is a new feature in Java 8, whi ...

Preface Share some common data cleaning methods of Mongdb Note: "Exceeded memory limit for $group, but didn't allow external sort. Pass allowDiskUse:true to opt in." causes and solutions: Reason During big data calculation and data statistics, each calculation task (job or task) will use independent and limited memory space. mongod ...

1. Project introduction 1.1) Project Blog Address https://rpc.cnblogs.com/metaweblog/yyh28 1.2 Functions and Features of Project Completion Analyse the file''Jimei University Enrollment Score. xlsx''to complete the following functions: 1) The average scores of different provinces in this batch from 2015 to 2018 at Jimei University. The column c ...

This note is excerpted from: https://www.cnblogs.com/zhili/archive/2012/07/18/ThreadPool.html Record the learning process for future reference. I. thread pool Foundation First of all, it takes a lot of time to create and destroy threads. Second, too many threads also waste memory resources. Therefore, creating too many threads through Thread cl ...

background As we all know, SimpleDateFormat in Java is not thread-safe and can cause unexpected problems under multiple threads.This article will explore the specific reasons why SimpleDateFormat threads are insecure to gain a deeper understanding of thread security. Example Simple test code that can cause problems when multiple threads call th ...