Basics of what is apk file and things inside it

APK file modding basic tutorial & description.

Download video tutorial made by lunadev & watch in it detailed...

Click here to download basic modding video tutorial

Info:video size 130mb... In English

Description or more detailed explanation by my own😉

Usually an APK file contains the following files:

1)AndroidManifest.xml

Application manifest file, version number, version name, permissions, application name, application icons, activities, services, broadcasts and other configuration information are in this file.

It's like brain to App😅

(we can play with this by changing or deleting or adding some stuff to it)

2)classes.dex

Android code file. In the development of Android applications, if the developers write Java codes, the codes will be compiled into many class files, and finally these files are combined into classes.dex file, so most of the java codes of applications are in this file. Some apks with bigger size may contains multiple dex files, such as classes1.dex、classes2.dex…

Essentially, any Activity, Object, or Fragment used within your codebase, will be transformed into bytes within a Dex file that can be run as an Android app.

Confused? Don't worry I'll explain in my upcoming page by videos on it with simple way to understand to you 

3)resources.arsc

Resource configuration file contains the string, theme, picture file index, layout file index and other information.

(mostly this file is encrypted if you view through mt manager... Apkeditor converters to res directly

res/

Resource folder contains pictures, layouts, menus and other files. The indexed files in the resources.arsc are stored in the directory (except for resource confusion)

4)assets/

Secondary resource folders (Not every APK has it). The files inside will not be indexed in resources.arsc.

(sometimes lib files,html files, pictures, videos, data like games, html,css, java,media, fonts,ttf files,binary files, etc in it) 

5)lib/

The folder contains .so library files. Such files are usually developed by C/C++.

Very important this files are used to run an app in a particular architecture device's... See my video tutorial I'll explain in it detailed 

6)META-INF/

It is often not useful, because it is just for storing information about signature.

(certificates of apk is stored in this folder)

This folder is under Unknown tab... 

Sometimes i delete signature files but sometimes it is useful so not delete them if they useful.. 

Now I'm explaining some important terms in modding ...

(a) APK Clone

In the Android system, the package name is the ID of each application. After the application is updated, the name, the picture and the interface may be changed. Only the package name can not be changed. For different applications, their package names should be different. Otherwise they will be considered the same applications.

Through this principle, you only need to change the application package name, so that you can install the same application twice or more in your device.

(b)Zipalign

zipalign is an archive alignment tool that provides important optimization to Android application (APK) files. The purpose is to ensure that all uncompressed data starts with a particular alignment relative to the start of the file. Specifically, it causes all uncompressed data within the APK, such as images or raw files, to be aligned on 4-byte boundaries. This allows all portions to be accessed directly with mmap() even if they contain binary data with alignment restrictions. The benefit is a reduction in the amount of RAM consumed when running the application.

This tool should always be used to align your APK file before distributing it to end-users. The Android build tools can handle this for you. Android Studio automatically aligns your APK.

Note:1)You must use zipalign at one of two specific points in the app-building process, depending on which app-signing tool you use...
          2)also if u use apksigner to sign then zipalign before you sign

(c)SAP or Antisplit

SAP means single apk package... 

Some apps use multiple or split apks bundled to build single apk to reduce the size of the app... 

So we cannot mod them until they converted in normal single apk... 

This method of converting SAP is called antisplit... 

You can do it just follow simple tool I'll provided and I'll explain in detail in my blog... 

(d) Decompile & Recompile(compile) 

Decompilation is sometimes used unethically, to reproduce source code for reuse or adaptation without permission of the copyright holder. So we need to decompile any apk to make changes to it... 

After completion of our mod then converting back to apk is called compile or recompile... While we recompile if we done any mistakes then it won't recompile so we need to rectify them and then recompile succeed... 

(e) Sign apk

The meaning of signature
When you modify an apk and do not sign it, you will find that you can not install successfully (unless you modify the system).so we need to sign apk after our modding... Complicated right? Don't worry we help you to teach you in detail by simply in another blog

(f) AAPT & AAPT2

AAPT means Android Asset Packaging Tool
So aapt checks less errors when compile apk and aapt2 checks max all errors of your mod... So it helps to rectify them and triggers you not to crash our mod after build is done...
(you will find in detailed in next tutorials by doing mods) 

🙃 Cool now you understanded some terms... Ok now you can do mod things but some more basic info you need to know how to use tools
Like apkeditor, apktool m, mt manager... Check remaining tutorials in my blog