Convert Your .apk files to .jar files

I have searched a lot for a bit of information on converting .apk files to .jar files. I will share it with you.Let's get sarted.

Download .apk file from market

• Download any app from the Android Market [Go]   [[Click and Plz wait for 5 seconds]] {Press small close button on top right}
• Install Astro File Manager from Android Market [Go]  [[Click and Plz wait for 5 seconds]] {Press small close button on top right}
• Open Astro > Tools > Application Manager/Backup and select the application to backup on SD card.
• Mount the phone as USB and access 'BACKUPAPPS' folder to find the apk of targetapp.(lets call this targetapp.apk).
• Copy it to your hard disk.

Decomiling apk to Dex format

• Download Dex2Jar [GO] [[Click and Plz wait for 5 seconds]] {Press small close button on top right}
• Android runs applications which are in Dalvik Executable (.dex) format.
• Run the following command to convert apk to jar.

dex2jar targetapp.apk file(./dex2jar targetapp.apk on terminal)

                                                 File 'targetapp.apk.dex2jar.jar' is created

[Click to Enlarge]

Viewing/Decompiling the Jar files to Java

Method 1 : Use JavaDecomiler (JD)

• Open 'targetapp.apk.dex2jar.jar' with jd-gui [Click to Download]  [[Click and Plz wait for 5 seconds]] {Press small close button on top right}
• File > Save All Sources to save the class files in jar to java files.

Method 2 : JAD

• Extract contents of jar file on to a folder named src.  Use and unarchival utility like 7zip.
• Keep 'src' folder in the same directory where JAD and targetapp jar is present.
• Open JAD in cmd and execute the following command

jad -o -r -sjava -dsrc src/**/*.class (./jad on terminal)

Now src will contain decompiled Java files ready for manual code review.

Source:- http://www.blacksecurityup.blogspot.com