It's easy
Get these tools:
1) dex2jar to translate dex files to jar files
2) jd-gui to view the java files in the jar
The source code is quite readable as dex2jar makes some optimizations.
Procedure:
And here's the procedure on how to decompile:
Step 1:
Convert classes.dex in test_apk-debug.apk to test_apk-debug_dex2jar.jar
d2j-dex2jar.sh -f -o output_jar.jar apk_to_decompile.apk
Note: In the Windows machines all the .sh
scripts are replaced by .bat
scripts
dex2jar documentation
Step 2:
Open the jar in JD-GUI