Programmer Group

catalogue 1. Array 1.1 concept 1.2 creation of array   1.3 array creation process 1.4 length of array 1.5 array variables 2. Tools 2.1 Arrays 1.Arrays.toString 2.Arrays.sort 3.Arrays.copyOf 1. Array 1.1 concept Array, marked with "[]", is used to store the aggregation of multiple data of the same type. If you wan ...

catalogue preface HashMap Base 1.7 Base 1.8 Traversal mode ConcurrentHashMap Base 1.7 Base 1.8 summary preface Like Map   Key Value   It is a very classic structure in software development, which is often used to store data in memory. This article mainly wants to discuss a concurrent container such as ConcurrentHashMap. B ...

Let's start with a question. How many steps does it take for a new machine to run a regular spring boot project? 1. Download and configure java environment, mysql environment and redis environment (step 6) 2. Initialize mysql database and import sql files (step 2) 3. Download the jar package and start (step 2) As like as two peas Ling Wan ...

reflex 1. Class loader 1.1 loading of class When a program wants to use a class, if the class has not been loaded into memory, the system will initialize the class through three steps: loading, connecting and initialization. load This is to read the class file into memory and create a class object for it. When any Class is used, the sy ...

What is Unsafe First of all, we say that the unsafe class is located under the sun.misc package in rt.jar. Unsafe translation is unsafe. This does not mean that this class is unsafe, but that it is unsafe for developers to use unsafe, that is, it is not recommended for developers to use unsafe directly. And there is no unsafe source code in th ...

1, One to many association configuration Database: master table, slave table, associated by foreign key Class: class A{ B b； } class B{ } Example: order and orderItem order entity class package com.sjy.entity; import java.util.HashSet; import java.util.Set; public class Order { // create table t_hibernate_order // ( // order_id i ...

         The last article talked about the use of remote tools to remotely deploy the service, which allows it to run in the background without hanging up. This can basically meet the needs of normal projects, but we can continue to optimize the operation on this basis and do better.     &nbs ...