Programmer Think

1, Keying status description Referring to the description on the official website, several keying states are introduced as follows: ValueState: save a value that can be updated and retrieved (as mentioned above, each value corresponds to the key of the current input data, so each key received by the operator may correspond to a value). This v ...

preface *** reference material: Deep understanding of String in Java 1, Analysis of the underlying source code of String class Let's take a look at the source code of the String class: public final class String implements java.io.Serializable, Comparable<String>, CharSequence { /** The value is used for character storage ...

Problem Description: In a chessboard composed of 2^k * 2^k squares, just one square is different from other squares. This square is called a special square, and the chessboard with a special square is called a special chessboard. When k ^ 4 is in different positions on the chessboard, there will be a special case, for example, when k ^ 4 is in ...

1, Use of File class 1. Use of file class Use of File class① An object of the File class that represents a File or a File directory (commonly known as a folder)② The File class is declared in Java Under IO package ③ The File class involves the creation, deletion, renaming, modification time, File size and other methods of files or Fi ...

Application of RabbitMQ in practical projects Business scenario explain: For some reasons, the specific business is not explained. The general business scenario is that module A will send A message to module B, and module B will update the local cache encache And module B is A cluster deployment in the project. Switch selection: 1. fa ...

summary Reflection is one of the features of Java programming language. It allows running Java programs to check themselves, or "self-examination", also known as "introspection". Reflection is so powerful that it can even directly manipulate the private properties of the program. We all have a concept in the previous study. ...

Hostnames are confused 1. Preconditions Install java1 8. Zookeeper is installed independently. There will be no detailed installation here 2. Download apache-pulsar-2.9.1-bin.tar.gz https://pulsar.apache.org/en/download/ 3. Initialize and create a cluster Cluster metadata initialization tip:  you only need to write these metadata once. b ...

TIP This article is included in< Introduction · YuQue >For more in-depth articles, please go to< Introduction · YuQue> . data type There are eight basic data types in the Java language: boolean/1byte/8char/16short/16int/32float/32long/64double/64 The eight basic data types are divided into four categories: ...

catalogue 1.C3P0 Preparation before use: Method 1: hard coding (database configuration is written into the code) Method 2: write configuration file and separate code and configuration (development recommendation) 2.DBCP Preparation before use: Method 1: hard coding (database configuration is written into the code) Method 2: write config ...

rdf-component-enum Do you worry about adding several methods to get values or enumeration every time you add an enumeration class? Although they are just copy and paste, they are still unbearable. The existence of this component is to solve this problem. 1, Effect This component provides the basic functions of enumeration and some commo ...