Programmer Think

Single column collection ArrayList Variable array, default capacity 10. Automatically move the following elements after inserting them Not thread safe Vector The main difference from ArrayList is that the thread of Vector is safe, and other usage methods are consistent with ArrayList LinkedList The bottom layer is realized by two-way lin ...

Day8 java exception concept Exception: in the Java language, abnormal conditions during program execution are called "exceptions" Exceptions (all abnormal conditions at runtime) that occur during the execution of Java programs can be divided into There are two types: Error: serious problems that cannot be solved by the Java vi ...

Use IDEA to create a new project for maven to manage spring boot (because the community version is used, the plug-in of alibaba is downloaded to help create ~) Pay attention to modifying the packge. If you use the plug-in, the packge under it will not change. It has always been (PIT) Top level parent project created successfully! The top-le ...

Header explosion, po2vo, vo2do, do2dto, a bunch of object attributes, take them out and stuff them in. If it were not for the layered anti-corrosion under the DDD architecture, I really want to connect it. That's BeanUtils Copyproperties ， in fact, there are not only this method but also 12 similar methods for object conversion, but overa ...

preface Old iron / old fellow friends are good! What ah Chang shared today is the commonly used Lombok annotation, Official address，github address Who doesn't know this little pepper when doing Java development. Lombok is a tool that can help us simplify and eliminate some necessary but cumbersome Java code through simple annotation, so as ...

[Spring Cloud Alibaba] Mybatis Plus persistence layer 1,Mybatis Plus Mybatis Plus is a domestic persistence layer framework. It is very simple to use here. It should be in Chinese! Mybatis Plus official website: https://baomidou.com/ Spring Cloud Alibaba integrates in the same way as Spring Boot No invasion: it is only enhanced wit ...

From the overall logic of the JVM in the previous article, this article will talk about the class loading mechanism Review some working models: one we wrote ourselves java file, compiled and generated Class file, will The class file is loaded into the JVM according to The different data information of the class binary file is allocated to ...

catalogue 1.3 thread status background 1. Creation status 2. Operable state 3. Inoperable state 4. State of death 1.4 thread scheduling 1.5 thread priority 1.6 daemon thread ​​​​​​​ 1.3 thread status background Threads have four states: creation state, runnable state, non runnable state and death state. 1. Creation status Af ...

Procedure requirements: 1. Randomly generate maze map The maze map needs to be randomly generated in the game and Java util. Random class uses the random number generation method provided by random class to randomly generate obstacles, paths or rewards. Maze map is represented and stored by two-dimensional array. 2. Judge whether the player ...

1 one to one query (many to one) Use the simplest User and Account model to analyze the multi table relationship of Mybatis. The User is the User table and the Account is the Account table. A User can have multiple accounts (Account), requirement: query all Account information and associate query order User information. Note: because an Accoun ...