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How can I get rid of unnecessary code in .apk file?

I have an empty project (no classes whatsoever, no activities), only a dependency to com.google.android.material:material:1.3.0 for the code to compile (there is a style defined which uses this).
I enabled shrinking option, yet, after generating the signes APK, there is a classes.dex file in the apk with a shitload of code, even though the app has no code. Why and how to I get rid of those, to make sure the apk contains only what is needed, no extra bloatware? Thank you.
This is the expanded apk:

For code shrinking please turn on Proguard and you have the option to customized Proguard rules as you need.
buildTypes {
release {
shrinkResources true
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
debug {
}
}

TRY 1
Open .jar file (appodeal.jar) and remove all .dex files.
TRY 2
Use the built-in inspection Java | Declaration redundancy | Unused declaration.
To run it on whole project go to Analyze -> Run inspection by name..., type Unused declaration and select desired scope. Then carefully check output and mark some classes as entry points if needed.
Select Unused declaration node in list and perform Safe delete action on all unused declarations at once.

After adding large png images .SO created leading to increase in app size

I replaced some png images in my project and the app bundle did not build successfully as the png files were too large each 2-3mb. I then changed the images with some jpegs which were a few hundred kb in size per file. After that when I built the app the size of the app went from 9mb to 27 mb. I analyzed the apk and most of the size is due to some lib files
I deleted the build folder to remove any old files but it did not help.I excluded all .so files but the apk is not installing without them. I tried making a bundle but that is also the same size.
What should I do to revert back to the old apk size.

Read Add multi-density vector graphics
Android Studio includes a tool called Vector Asset Studio that helps
you add material icons and import Scalable Vector Graphic (SVG) and
Adobe Photoshop Document (PSD) files into your project as vector
drawable resources. Using vector drawables instead of bitmaps reduces
the size of your APK because the same file can be resized for
different screen densities without loss of image quality.
You should use SVG images instead of JPG/PNG.
To make your app as small as possible, you should enable shrinking in your release build to remove unused code and resources. When enabling shrinking, you also benefit from obfuscation, which shortens the names of your app’s classes and members, and optimization, which applies more aggressive strategies to further reduce the size of your app.
Read Shrink, obfuscate, and optimize your app
android {
buildTypes {
release {
// Enables code shrinking, obfuscation, and optimization for only
// your project's release build type.
minifyEnabled true
// Enables resource shrinking, which is performed by the
// Android Gradle plugin.
shrinkResources true
// Includes the default ProGuard rules files that are packaged with
// the Android Gradle plugin. To learn more, go to the section about
// R8 configuration files.
proguardFiles getDefaultProguardFile(
'proguard-android-optimize.txt'),
'proguard-rules.pro'
}
}
}

I think images are not the issues from the dex files you have created I think you have included big libraries or many libraries?

Try to set minifyEnabled true to shrink resources in gradle file.

Use NDK abiFilters in your app module’s build.gradle like this:
android {
defaultConfig {
//...
ndk {
abiFilters "armeabi-v7a", "x86", "armeabi"
}
}
}
You can also exclude the specific *.so files that you don't want:
packagingOptions {
exclude 'lib/arm64-v8a/lib.so'
exclude 'lib/mips/lib.so'
}

How to exclude resources or aar files from main APK

As i need to reduce the size of APK file, I have followed Apk Expansion guide to divide APK in chunks.
The Downloader library defines ways to download the expansion file, but i need to know the way to exclude resource files and aar files from the apk.
I found following, but these are neither removing any resource-drawable files nor any arr files, and the size of apk remains same.
For testing purpose, i have added drawables of around 4 MB and couple of arr files of size 3 MB. I am creating apk from Build->Build APK option. I don't know if following will effect only on signed APK.
sourceSets {
main {
resources {
exclude '**/drawable/*'
}
}
}
android {
packagingOptions {
exclude 'lib/armeabi/a.so'
}
}

If there are specific resources you wish to keep or discard, create an XML file in your project with a <resources> tag and specify each resource to keep in the tools:keep attribute and each resource to discard in the tools:discard attribute. Both attributes accept a comma-separated list of resource names.
<?xml version="1.0" encoding="utf-8"?>
<resources xmlns:tools="http://schemas.android.com/tools"
tools:keep="#layout/l_used*_c,#layout/l_used_a,#layout/l_used_b*"
tools:discard="#layout/unused2" />
Save this file in your project resources, for example, at res/drawable/keep.xml. The build does not package this file into your APK. This way you can customize which resources to keep.

Expansion files may not contain any executable code. This is partly a Google Play policy, but also for security. Because they are written to a directory accessible to both your app and Play, and possibly to an SD card, if you put code their it would open your app to security exploits.
Because of this, you don't want to put AAR files in expansion files, as these normally have code. And many resources might not be appropriate, as these get compiled with your app and so have resource ids etc. Instead you should split out large elements that are not part of the explicit compile. Good candidates are things like:
Open GL textures
large sound files for sound effects
large level data or maps for games
large images
All of these could potentially be in the assets directory of your app and are prime candidates for expansion files.
If you have none of the above, if you are going over 100Mb in size it is likely that you are not Proguarding your code correctly, and including a lot of code your app doesn't use. If this is the case, then learning to use Proguard correctly is probably a bigger improvement than switching to expansion files. SO users may be able to advise you more if you can say where the size in your APK is going? How much on images? How much on executable code? Are you using Android Studio and java, native code, or a technology like Unity? All of these have slightly different approaches to APK size minimization.

There are 2 things that you can do.
Firstly, you can use Lint. Lint will help to highlight and remove all the resources that you are not using in your code including the drawables.
Second you can use Proguard. Using Proguard you can choose which version of APK you want to shrink including the debug(or main, as in your example) version. Just insert the following code.
android {
buildTypes {
debug {
minifyEnabled true
useProguard false
proguardFiles getDefaultProguardFile('proguard-android.txt'),
'proguard-rules.pro'
}
release {
minifyEnabled true
proguardFiles getDefaultProguardFile('proguard-android.txt'),
'proguard-rules.pro'
}
} }

Exclude xml files from compilation android [resource shrinking]

I would like to use some xml files as mockups to preview different states of a layout, but I don't want to include it in the apk because thes xml files are only dedicated to preview purposes. I would like to tell gradle which files/directories to ignore for resources.
It would also be useful to easily reduce apk size for low memory devices by using products flavors, in a similar way as this excellent article explains.
Maybe proguard could help?

If you are using the android studio you can add resources by build flavors your want example you can add string resource for debug build only and different string resource for main release build. You just right click add a xml resource choose a resource type and specify the source set.
if you add a layout for debug flavor only and not in main release then everytime you sign an apk the those layout will not be included in apk. Hope it helps :)

We call it "Resource shrinking". All info about it is here.
Look at shrinkResources true. Build system will try to find unused resources files with this flag, and will remove them from the build. You can add it to your debug buildType, and on any build flavor.
android {
...
buildTypes {
release {
minifyEnabled true
shrinkResources true
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}

Android : Automatically remove unused images from project bundle

I am developing an android project that is pretty big and have many images in drawable folder. Many of these images are not being used in the project (because they have been replaced) and they consume valuable space. Is there any way that I could automatically find those images and delete them, instead of searching through each image in the project?

Some tools I have used are
android unused resources
and
android lint
One of the features does say
Unused resources

We open sources a tool that removes all unused resources automatically from your project based on android lint output.
Even unused strings and other 'inline' resources.
https://github.com/KeepSafe/android-resource-remover

Now we can do it automatically with gradle
buildTypes {
release {
minifyEnabled true
shrinkResources true
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
More details are here
https://sites.google.com/a/android.com/tools/tech-docs/new-build-system/resource-shrinking