Problem shooting

Go to /var/log/kafka, find the ERROR message in the newest generated file.

Solution

Unable to start kafka with zookeeper (kafka.common.InconsistentClusterIdException)
Delete/var/lib/kafka/meta.properties
And it worked for me:)

Show case, code -> Todolist app

Day 1

Why Coordianate Layout?

• I want ToolBar to collapse or hide. Google made it really easy by introducing AppBarLayout & CollapsingToolbarLayout, which both work best under a CoordinatorLayout.

Why Relative Layout?

• RelativeLayout enables you to specify how child views are positioned relative to each other.

Trade-off using @Parcelize annotation

We know implementing Parcelable on an entity class so the entity object will be put into an Intent object and passed between activities/fragment. Is it a good practice? What about Repository pattern? android - Is it good practice implementing Parcelable on a Room database entity? - Stack Overflow

Additional knowledge

• ellipsize: What does ellipsize mean in android?
• tool-attributes: Tools attributes reference tldr: tools:text means the text won't be generated into APK

See what's installed:
archlinux-java status
Get a name of version you want to use, then issue this command,
sudo archlinux-java set JAVA-X-JDK JAVA-X-JDK is the name of the result from the status command.

Got more familiar using Material theme now, and learned a lot about:

• write clear and clean code
• user experience, like adding ScrollView to prevent element from being truncated . This websize helps with Material tools: Resources - Material Design

Also I made an app along the course named TipTime which calculates the tip. Ref: Android-basis: TipTime

It's a beautiful UI displaying a classical Chinese poetry, I wrote it just by adding TextView programmatically so a poem can be arranged vertically😅. It still needs some improvements in terms of UI, and I'll add more features to it soon :)
The elegant open source app: A Full-Stack mobile app, including Android & Server, Simple-Poem 简诗. You can write poem in graceful & traditional Chinese style.

Check the MYSQL Reference Manual

MySQL :: MySQL 5.6 Reference Manual :: B.3.2.2 Can't connect to [local] MySQL server
I know there are two ways of connecting the mysqld server in Unix, So I quckly found that the /tmp/mysql.sock was missing.

Solution

資料庫中mysql.sock不存在問題，Can 't connect to local MySQL server through socket '/tmp/mysql.sock '(2) " - IT閱讀
Then use systemctl start mysqld.service to start the server.
Use systemctl status mysqld.service to check the status of the server.

Music and code, but most of all: Have fun!

I really appreciate the combination of music and coding, hence I have so much fun playing around with it :-)

What is Living code and how you can try it on youself?

Sonic Pi - The Live Coding Music Synth for Everyone
https://sonic-pi.net/

(Solved)Installation Issue in Archlinux distro

Unable to start on Manjaro Linux · Issue #2341 · sonic-pi-net/sonic-pi

使用WechatMomentScreenshot

这是一个开源的朋友圈转发截图生成器，适用于当你被迫转发文案集赞才能使用某种产品的情景。我在Chrome和Firefox都简单手动测试了一下功能。发现在Chrome上生成不了图片。我就去项目的issue逛了一下看到有人是因为使用广告拦截插件而看不到生成的图片。我把注意点转向了Chrome上安装的插件🤔

找到你了！ CanvasFingerprintBlock插件

非常粗暴地把每个插件都试了一遍，最后发现是这个插件在起作用。去Chrome web store看这个插件的介绍，再结合项目main.js里对toDataURL() 的使用，基本上这个插件是在防止生成的canvas向网站发送用户的个人数据。

Such websites do this by painting an image on a hidden HTML element and then taking a snapshot of it and posting the snapshot back to themselves. Because the exact pixel values in the drawn canvas can differ subtly from one set of hardware to another, these websites can use those differences to distinguish between visitors as well as to recognize specific visitors from one visit to the next.
我就很好奇是怎么从生成的canvas中的这些pixel values来辨别用户的。于是，我找到了一些解释。

Canvas fingerprinting的基本原理

Canvas fingerprinting works by exploiting the HTML5 canvas element: when a user visits a website their browser is instructed to “draw” a hidden line of text or 3D graphic that is then rendered into a single digital token, a potentially unique identifier to track users without any actual identifier persistence on the machine. Variations on installed GPU model, operating system and overall system performances cause the variations in the rendered digital token.

参考：

• https://blokt.com/guides/browser-fingerprinting

• https://en.wikipedia.org/wiki/Device_fingerprint

我还从 https://coveryourtracks.eff.org/ 这个网址上测试出我的Timezone, BrowserPlugin details（存在插件漏洞被利用风险）, Device memory等很多个人信息呢:(

可以做点小小抵抗

除了 Coveryyourtracks 这篇文章提到的措施外，依据不同的需求分开使用浏览器也是个办法。

What it looks like