An app has private data and optionally public data. The private data goes inside a directory with name as the package name and located inside /data/data/ - an ordinary user/app cannot read that data. The public data may either go into internal SD card or external SD card, whichever is set as default and the app having permission to write it. /sdcard/Android/data is where often the public data goes. Some apps opt to create a dedicated folder under the root of default storage as well.
Now, how do you access the private data?
Since you noted that the app is in development, it may be possible that it is marked as debuggable1 (
android:debuggable="true"). If that's the case, then setup adb in PC and execute the command:
adb shell run-as PACKAGE # PACKAGE is the package name of your app
Note: run-as would work only for debuggable apps.
run-as would drop you into the data directory of your app where you can see whatever you intend to see.
Follow this answer from marmor as an example.
If the app hasn't explicitly declared itself not to be backed up1 (
android:allowBackup="false"), you can use adb to backup the app. To do so, execute the command:
adb backup PACKAGE
This will create a file named backup.ab in the working directory from where adb is called.
In order to extract the data from the backup, follow an answer from here: How do you extract an App's data from a full backup made through "adb backup"?
- Yes, if the first two methods fail, then the Android should be rooted. Once you've root, you can use a file explorer or even a terminal emulator app to read the desired data.
1 Unless there is an explicit app to tell you so, you would be required to read the manifest of the involved app in order to ascertain whether it is debuggable or disallows backup. Axel (XML Editor / Viewer) and App Browser can help you to read manifest.