2017-10-06

The difference between a case class and a normal class in Scala

What is a case class like12345678case class Person(name: String)object CaseClassTest { def main(args: Array[String]): Unit = { val person = Person("John") println(person.toString) &#

Coding

2017-10-05

Some Linux Commands

:-Take ${val1:-val2} for example, if val1 is unset or null, return val2, otherwise return val1. Example: 123456#!/bin/bashdefault="default"preset="preset"value="This is ${preset:-"$default"}

Coding

2017-10-03

newInstance in Java

IntroductionnewInstance is used to instantiate an instance of a class dynamically. Here is an example written in Scala. 1234567891011class Printer() { def print(): Unit = { println(s"pri

Coding

2017-10-02

When and how to use InheritableThreadLocal

Today I was reading Spark’s source code, and found InheritableThreadLocal in it. Little information could be found online about this class, so I decided to write a blog to illustrate how to use it, ba

Coding

2017-09-09

The difference between wait and sleep

wait and sleep can both be used to put a thread into sleep and wait for a while. So what’s the difference? To find it out, we need to figure out how to use them first. WaitTo use wait, you have to put

Coding

2017-07-15

Leetcode: Combination Sum II

ProblemGiven a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combi

Coding

2017-07-09

Why is Kafka so fast

As we all know that Kafka is very fast, much faster than most of its competitors. So what’s the reason here? Avoid Random Disk AccessKafka writes everything onto the disk in order and consumers fetch

Coding

2017-05-18

kafka in a nutshell

IntroductionKafka is a distributed publish-subscribe messaging system that is designed to be fast, scalable and reliable. It can be used in data analysis, stream processing and other similar tasks. Th

Coding

2017-05-15

what does "this" refer to in javascript?

Introductionthis in javascript is always a mysterious thing. Some programmers who have written a lot of javascript code still cannot tell the value of this every now and then. So today, I decided to w

Journal

2017-05-15

re-embrace hexo and hueman

About a month ago, I started writing blogs in Chinese using WordPress. I stuck to the plan for about several days then decided to use English instead. The reason is unbelievably simple: typing English

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