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enumeration Format of enumeration Permission modifier enum enumeration name{               Example 1, example 2, example 3, example 4; } package com.meiju; public enum Level2 { LOW(1),MEDIUM(50),HIGH(100); private int levelValue; private Level2(int levelValue){ this.levelValue=le ...

MacBook Air M1 is configured with java development environment Maven + IDEA 1. JDK configuration At present, Zulu JDK supports M1 chip. Download Azul Zulu Builds of OpenJDK After downloading, click Install and follow the steps. After that, enter java -version on the console openjdk version "17.0.1" 2021-10-19 LTS OpenJDK Runtime Environment ...

IO stream First, we should understand external memory, memory and cache io is divided into input and output: Personal understanding: Output stream: output the file from the idea Input stream: read the file to the idea Input and output can be divided into: Byte stream: the smallest data unit in a data stream is bytes Output: OutputSt ...

Preparation for multi table query: three tables are created. Previously used user table, newly created role table, account table, user_role table. The specific parameters in the table are as follows: user table (mainly the header, which is filled in by itself): role table: account table: user_role table: After these classes are created, r ...

Catalog 1. Problem Description 2. Writing Code + Packaging Project in intellij idea 3. Upload jar package to Linux in xftp 4. Preparing input data + Running jar package + Viewing input results in hadoop 1. Problem Description With MapReduce, for each user, A suggests 10 users who are not friends with A, but have the most common friends w ...

shell script deployment springboot (Revised) explain The shell deployment springboot was sorted out before website: https://blog.csdn.net/shaoming314/article/details/120145215 However, the shell script does not have the option to stop, view and restart the service. It is not very good. This revision supports the options of stopping, restart ...

1. Define your own database and data table 2. Access the defined data table through JDBC and insert 2 records. Requirements: 1. Submit SQL statements defined in database and data table; 2. Submit program implementation process; 3. Submit program running results. This is a small class assignment assigned by my teacher. What is JDBC JDBC(Jav ...

HTTP protocol Chapter 1 Introduction to HTTP protocol [the external chain image transfer fails. The source station may have an anti-theft chain mechanism. It is recommended to save the image and upload it directly (img-grbtid56-1637415789041) (Shang Silicon Valley Zhang Chunsheng _httpprotocol. assets/timg.jpg)] HTTP hypertext transfer ...

Key points of Java basic syntax Type conversion 1. Basic data type Conversion In Java programs, the values of different basic data types often need to be converted to each other. The seven numeric types provided by java language can be converted to each other. There are two conversion methods for basic data type conversion: automatic typ ...

User login 1 user login persistence layer Learning video address [actual combat full version of SpringBoot project] actual combat of SpringBoot+MyBatis+MySQL computer mall project_ Beep beep beep_ bilibili 1.1 planning SQL statements to be executed The SQL statement to be executed by the user login function is to query the user data accordi ...