Extracting the Java source code

The first objective of reverse engineering is to get the original source code with maximum accuracy. As we have the application package downloaded on our Ubuntu virtual machine, let's use the JADX tool to get the Java code.

However, it might also be a good idea to simply unzip the APK and extract its contents to see what's inside:

Figure 3.5 – Extracted contents of the APK

In order to use the JADX tool, open the directory where you extracted the JADX .zip file (as explained in Chapter 2, Setting Up a Mobile App Reverse Engineering Environment Using Modern Tools). Once in the directory, right-click to select the Open in Terminal option. In the opened Terminal window, type the following command to run JADX:

# cd bin/
# ./jadx-gui

In the JADX window, open the APK file you just downloaded. Refer to Chapter 2, Setting Up a Mobile App Reverse Engineering Environment Using Modern Tools, to see how to do this...