Android application package
|Internet media type|
|Type of format||Package format|
|Container for||Mobile apps|
|Extended from||JAR and ZIP|
APK is analogous to other software packages such as APPX in Microsoft Windows or a Debian package in Debian-based operating systems. To make an APK file, a program for Android is first compiled using Android Studio, and then all of its parts are packaged into one container file. An APK file contains all of a program's code (such as .dex files), resources, assets, certificates, and manifest file. As is the case with many file formats, APK files can have any name needed, provided that the file name ends in the file extension ".apk". APK files can be used to downgrade apps and games to an older version (e.g. downgrade app or game version from 78.9 to 55.1) by uninstalling the upgraded app or game and installing the older version via APK file (you need to turn on "Unknown Sources" setting in phone settings menu). This can be done for various reasons, such as an upgrade causing the app to repeatedly freeze and/or crash, the upgrade changing the app drastically (e.g. background too dark or too bright or preferred features not present, changed, or hidden), or restoring/removing something that the upgrade removed or installed. APK files can also be a solution for installing apps/games that may not be accessible through standard methods due to restrictions that a country may have set to prevent usage of the software .
An APK file is an archive that usually contains the following files and directories:
MANIFEST.MF: the Manifest file
- The certificate of the application.
CERT.SF: The list of resources and a SHA-1 digest of the corresponding lines in the MANIFEST.MF file; for example:
Signature-Version: 1.0 Created-By: 1.0 (Android) SHA1-Digest-Manifest: wxqnEAI0UA5nO5QJ8CGMwjkGGWE= ... Name: res/layout/exchange_component_back_bottom.xml SHA1-Digest: eACjMjESj7Zkf0cBFTZ0nqWrt7w= Name: res/drawable-hdpi/icon.png SHA1-Digest: DGEqylP8W0n0iV/ZzBx3MW0WGCA=
lib: the directory containing the compiled code that is platform dependent; the directory is split into more directories within it:
armeabi: compiled code for all ARM based processors only
armeabi-v7a: compiled code for all ARMv7 and above based processors only
arm64-v8a: compiled code for all ARMv8 arm64 and above based processors only
x86: compiled code for x86 processors only
x86_64: compiled code for x86 64 processors only
mips: compiled code for MIPS processors only
res: the directory containing resources not compiled into resources.arsc (see below).
assets: a directory containing applications assets, which can be retrieved by
AndroidManifest.xml: An additional Android manifest file, describing the name, version, access rights, referenced library files for the application. This file may be in Android binary XML that can be converted into human-readable plaintext XML with tools such as AXMLPrinter2, apktool, or Androguard.
classes.dex: The classes compiled in the dex file format understandable by the Dalvik virtual machine and by the Android Runtime.
resources.arsc: a file containing precompiled resources, such as binary XML for example.
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