[Android SDK] Get source code from APK using dex2jar

1.- Obtain APK (rooted phone, or Titanium Backup/AppMonster)

2.- Rename APK to zip, unzip it

3.- Open command line tool, go to your dex2jar installation folder and type
./d2j-dex2jar.sh ../myapp/classes.dex

This will output a .jar file with the code

4.- Open JD-GUI and open .jar file obtained in step 3