Android Reverse Engineering and Decompilation

Reverse engineering of android java app using apktool, dex2jar, jd-gui to convert .apk file to .java.

By reverse engineering of android app (.apk file) we can get following :

  • understand how a particular UI in an App is constructed
  • reading AndroidManifest.xml – permissions, activities, intents etc in the App
  • native libraries and images used in that App
  • obsfucated code ( android SDK, by default, uses ProGuard tool which shrinks, optimizes, and obfuscates your code by removing unused code and renaming classes, fields, and methods with semantically obscure names.


Required Tools :

Download the followings first.

Using ApkTool

- to extract AndroidManifest.xml and everything in res folder(layout xml files, images, htmls used on webview etc..)

Run the following command :

>apktool.bat d sampleApp.apk

It also extracts the .smali file of all .class files, but which is difficult to read.

##You can achieve this by using zip utility like 7-zip.

Using dex2jar

- to generate .jar file from .apk file, we need JD-GUI to view the source code from this .jar.

Run the following command :

 >dex2jar sampleApp.apk

Decompiling .jar JD-GUI

- it decompiles the .class files (obsfucated- in case of android app, but readable original code is obtained in case of other .jar file). i.e., we get .java back from the application.

Just Run the

jd-gui.exe and File->Open to view java code from .jar or .class file.

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Reference: Android Reverse Engineering – decompile from our JCG partner Ganesh Tiwari at the GT’s Blog blog.

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3 Responses to "Android Reverse Engineering and Decompilation"

  1. With AndroChef Java Decompiler you can decompile apk., dex, jar and java class-files. It’s simple and easy.

  2. Freeman Mobile says:

    This way is just fine!
    But JD-GUI homepage has changed!
    Follow this tutorial to get updated link of JD-GUI
    How to decompile Android APK file

  3. Venkatesan says:


    I am very much eager to become a very good Android Development Engineer.I need one help from you.Currently I am having Source files,fully layout file and a manifest file.Will u go through it and compile it and help me.This project will help me out to become a very good Android Engineer.please help me.

    Thanks and Regards,

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