A modern programming language that makes developers happier.

kotlinlang

`Day13`
• Finished Lesson 1 in Developing Android Apps with Kotlin
    ◦ Tips for optimizing code, making apps more efficient
        ▪︎ Using late initialization to handle unnecessary references to a non-null variable
        ▪︎ Reducing app size by using androidx compatibility library
        ▪︎ Using app:src produces png files in lower API versions, which can lead to a big fat app 
    ◦ Various usage of namespace (tool - resource preview / app - custom libraries etc.)
    ◦ Gradle basics (manage compilation, dependencies, devices, app signing, tests)
        ▪︎ click run -&gt; (gradle compiles code, resources, manifest, etc.) -&gt; APK built -&gt; (Android Studio transfers APK to device) -&gt; app becomes installed
        ▪︎ Two types of build file(project-wide build file, module specific build file)
• Almost halfway through Lesson 2 in Developing Android Apps with Kotlin
    ◦ UI, layouts
        ▪︎ Tips (component tree seems useful to control hierarchies exactly as intended / should ‘refactor’ instead of just modifying / run-reformat code)
        ▪︎ Extracting Android Style seems useful to make the layouts consistent / Padding vs. Margin
`Self-Comment`
• A simple question to check - How can I know (estimated) app size of my app? I really loved that idea of using androidx compatibility library to get rid of useless pngs, but how can I know the before/after app size it takes?
• Installed Key Promoter X plugin - woo nice shortcut suggestions, thanks Bryan
• Realized that there were so many things I used without understanding, and that I was using less than half of Android studio’s features. BTW for theoritical stuffs, playback 2x seems fine. For hands-on tutorials, playback 0.5x and  skimming thru the scripts and following is fine.
• I really love my worcation/workation (closer to latter one I think..), only thing but I can’t use double monitor. Found a free coworking space nearby, but nobody uses - woohoo. About to spend thur&amp;friday here.
`GoalsTomorrow`
• Finish Lesson2, move on to Lesson3

First comment here :wave:
&gt; A simple question to check - How can I know (estimated) app size of my app? I really loved that idea of using androidx compatibility library to get rid of useless pngs, but how can I know the before/after app size it takes?
For the self-comment above, have you tried <https://developer.android.com/studio/build/apk-analyzer|APK Analyzer>? You can analyze your APK with this tool embedded in AndroidStudio (Just drag-and-drop `.apk` file to AndroidStudio). BTW, APK is basically a zip file, you can just `unzip xxx.apk -d dirname` to unzip APK. APK Analyzer is better than unzipping, but the basics are the same. To reverse-engineer further, you need ApkTool or Java Decompiler.
You can navigate `res/` folder to see what resources are in your APK. Since APK is like a zip file, you can guess that the impact of getting rid of useless png files is compressed volume of remove png files.

For APK size optimization, try <https://developer.android.com/studio/build/shrink-code|Shrink, obfuscate, and optimize your app> to see how things work. `Code Shrinking` or `Resource Shrinking` is often called as `Tree Shaking` in JavaScript(See <https://webpack.js.org/guides/tree-shaking/|here> for the official docs and see <https://itnext.io/under-the-hood-of-web-bundlers-e-g-webpack-926e868f7f5e|here> for under the hood).

Ohhhh thanks JoonHo Park for a quality answer, your comment really helps. I just skimmed that medium article, cool. I must read that thoroughly again tomorrow, seems worth it. BTW I really like your comment and also the way you develop your explanation. Hope I can give such qualitative guide to someone too.