Android optimize journey

This is how I reduce my Android app from 4.3 MB to 23.3 KB in size.

I'm gonna to make Yeeeeet

Yeeeeet is an Android application which allow user to download Instagram photos, videos to their smartphone by sharing Instagram posts to it.

So basically, Yeeeeet need a method to get a metadata (json) from Instagram, JSON parser and method to download file to store the media in storage.

To download metadata from Instagram, I use AsyncHttpClient class as below:

import com.koushikdutta.async.http.AsyncHttpClient;
import com.koushikdutta.async.http.AsyncHttpGet;
import com.koushikdutta.async.http.AsyncHttpResponse;

To parse JSON string, I use Gson:

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;

To download & store media files, I use Ion:

import com.koushikdutta.ion.Ion;

This is a build.gradle file. TBO, I don't care much about these implementation lines (just copy from another project), so I can code my app as quick as possible:

dependencies {
    implementation 'org.slf4j:slf4j-simple:1.7.24'
    implementation 'com.google.code.gson:gson:2.8.5'
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.github.ThinhVu:javaext:1.0.4'
    implementation("com.squareup.okhttp3:okhttp:4.9.3")
    compile 'com.koushikdutta.ion:ion:3.1.0'
}

You can find the source for this application at here.

---

As a lazy developer, I installed the Debug version of Yeeeeet to my phone using Android Studio debugger.

My phone storage have almost 64 GB of ROM, so I don't care about storage much.

But one time, when starring over my installed apps, I see there is a problem.

Yeeeeet have approx ~14 MB in size.

Why? What?

Why app size is so large? It only has more than 100 lines of code.

What is the problem?

APK analyzer

First thing first, I need to see what's inside the Apk.

./gradlew app:assembleDebug, then double click to the app-debug.apk in /debug folder.

I don't know why the app took 14 MB in size (maybe it included Android Studio's junk code: breakpoints, etc, ... )

The APK size is 4.3 MB in size as image above (corresponding to this commit)

As you can see, there is a lot of things included in the APK (androidx, kotlin, java9, okhttp3, okio,...)

It's seem like an apk included everything in the libs, even the one it doesn't use. So I think it's time to remove unused stuff (code, resources, ...)

Enable Proguard

debug {
    shrinkResources true
    minifyEnabled true
    proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}

then assembleDebug again.

Now the apk look like that:

The app size decreased by half in size in just one step. Excellent. But still large.

People can land on the Moon with 4 KB in RAM, approximately 64 KB in ROM. With the current size of my app, it must land people on Mars, not just download a few Instagram pictures.

It means I have to do something to decrease the size furthermore.

Using Android supported class instead of libraries

• remove Gson, using org.json for JSON parsing.
• remove AsyncHttpClient & Ion, using HttpURLConnection to download Instagram metadata and media resources.
• remove androidx stuff (which cost approximately 1.2 MB in size), just using components in android package for User interface.
• remove all resources (icon, themes), just keep the largest icon, so it can be used on any devices.

You can see the commit at here

then assemble the debug apk again. This is the result:

Now I'm happy with it.