Java ConcurrentHashMap
ConcurrentHashMap is designed to support concurrent access from multiple threads without the need for external synchronization. It achieves this by using var...
Posts by Category
Blog
Certbot on Oracle Cloud VM
Try to get a certificate from Let’s encrypt on Oracle’s compute instance (vm) with command certbot certonly --standalone but keeps getting error: Certbot fai...
AWK 101
Note for Learning Awk Is Essential For Linux Users download awk is a tool to process text, line by line. Variable $0 means whole line, $1 means the fi...
Java Features By Version
Java 8 https://www.oracle.com/java/technologies/javase/8-whats-new.html Functional Interfaces and Lambda Expressions Default and static metho...
PlantUML in VS Code
Test #@startuml class ExampleClass { -mPrivate: String +mPublic : int #mProtected: boolean ~mDefault: float mNothing: long +void pu...
Lesson Learned - Java Timer
Issue When you use Java Timer (java.util.Timer) to set a task for future execution, you should be really careful. Java Timer use currentTimeMillis, which wi...
Java SE: Programming Complete - 9
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Collections ####
Java SE: Programming Complete - 8
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Arrays and Loops Arrays An array is a fixed-length collection of eleme...
Java SE: Programming Complete - 7
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Interface Java Interface An interface defines a set of features that c...
Java SE: Programming Complete - 6
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Inheritance Extend Classes java.lang.Object is an ultimate paraent of ...
Java SE: Programming Complete - 5
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Improved Class Design Use Method Overloading Two or more methods, with...
Java SE: Programming Complete - 4
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Classes and Objects Designing Classes Description of the package that ...
Java SE: Programming Complete - 3
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Text, Date, Time and Numberic Objects String String is a class (not a ...
Java SE: Programming Complete - 2
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Primitive Types, Operators, and Flow Control Statements Whole Numbers ...
Java SE: Programming Complete - 1
https://learn.oracle.com/ols/course/java-se-programming-complete/82508/85200 Introduce to Java How Java Works Source code is plain text .java Com...
Statistics
统计学 基本概念 正态分布 － 概率分布曲线，中间高，两边低，左右对称 描述正态分布的两个参数 峰值（平均值） － μ (miu） 标准差 － σ （sigema） 对于正态分布，无论 μ 和 σ 的值如何，都满足 68－95－99.7 法则，即 68%的数据会落在 μ±σ 区间，95%的数据...
Get Android Build Info from code
You can get build info from android.os.Build class. But there are some informations are hidden, like IS_USERDEBUG etc.
C++ Concurrency
https://www.youtube.com/watch?v=F6Ipn7gCOsY What is concurrency? Concurrency means doing two things concurrently — “running together.” Maybe you’re ...
AOSP Tips
Notes for https://youtu.be/NsqFOSzoYE8 Android SDK Search chrome plugin This is a very useful plugin when you checking Android document and source code...
VSCode Plugins
For All Purpose Partial Diff ★ ★ ★ ★ ★ Compare (diff) text selections within a file, across files, or to the clipboard Remote Development Pack ★ ★ ★ ★...
Work Behind Proxy
Work Behind Proxy Many easy tasks can’t be easily done if you work behind proxy. Snap sudo snap set system proxy.http=http://<username>:<password...
Java - Volatile or Synchronized
Volatile There are two features when talking about thread-safe (Concurrency) Mutual Exclusion: It means that only one thread or process can execute a bl...
Ubuntu Powerline Setup
Powerline is a statusline plugin for vim, and provides statuslines and prompts for several other applications, including zsh, bash, fish, tmux, IPython, Awes...
Java Unit Test: JUnit5
Source JUnit5 Basics JUnit 4 & 5 Annotations Lifecycle/Hook Points For JUnit5, it’s @BeforeAll @AfterAll and @BeforeEach...
Input Unicode Character by Adb
Source https://stackoverflow.com/questions/14224549/adb-shell-input-unicode-character adb shell input doesn’t support unicode character, there is an ope...
Output Gradle Test Result to Console
Source https://stackoverflow.com/questions/3963708/gradle-how-to-display-test-results-in-the-console-in-real-time The gradle test output doesn’t make an...
UML Quick Reference - Class Diagram
Source https://www.visual-paradigm.com/guide/uml-unified-modeling-language/uml-class-diagram-tutorial/, Reference http://ifeve.com/uml-intro/ Class Diag...
Heroes 3 Tips
兵种数量 几个（few）：1-4 一些（sevral）：5-9 一群（pack）：10-19 许多（lots）：20-49 很多（horde）：50-99 大群（throng）：100-249 大量（swarm）：250-499 大批（zounds）：500-999 无数（...
Java - Lambda
Lambda Before Java SE 8, anonymous classes were typically used to pass functionality to a method. This practice obfuscated source code, making it harder to ...
Andriod Log
I was thinking how to use log on Android properly, and can control it without re-compile your app. Here is what I found. Long story for short, you should do...
Java Note
Note for Advanced Java Programming Generics Generic method public <T> List<T> arrayToList(T[] array, List<T>) { for (T t : array...
Docker ENTRYPOINT vs CMD
Both ENTRYPOINT and CMD allow you to specify the startup command for an image, but there are subtle differences between them. There are many times where you’...