How to Use Assert on Android Devices

How to use assert in android?

Assert won't work in Android because most of the time a person isn't running in debug mode, but rather some optimized code. Thus, the proper solution is to manually throw an exception, with code like this:

if (obj==null) throw new AssertionError("Object cannot be null");

It should be noted that by design, Asserts are intended for debug code, and not for release time code. So this might not be the best use of throwing an Assert. But this is how you can do it still, so...

How to use assert in Android Studio

The adb shell setprop debug.assert 1 from your referred question is to be executed on the device you are testing on, so you could whip up a script or even create a custom gradle task for that (gradle docu).

In general I'd recommend to also have your checks in production and handle them in a proper way. A simple solution would be to throw a RuntimeException. With checked Exception you could even handle the recovery from this errorneous states / misuses of your api.

Furthermore, it would make sense to add proper tests that ensure, that your code/APIs only emit "valid" values that can be handled by the rest of your code.

Assertions Android Programming

Since the question was if it is possible... Yes it is possible but I go along with CommonsWare that asserions should be avoided.

Anyway see Can I use assert on Android devices? for how to use Assertions on Android

Are asserts available on Android?

Yes, they are available.

They are disabled in emulator by default. You will need to add -shell -prop debug.assert=1 command line parameters to Additional Emulator Command Line Options at the run configuration you're using to run your app.

The other thing you should be aware of is that your application installed on a device will not take into account assertions - they will be ignored.

Android Studio assert not working

Apparently, (as stated in the comments) assertions are disabled by default but encouraged by Android Studio.

In this manner, the "problem" can be classified as a misleading UX issue rather than a technical problem.

better way to do Debug only assert code

I think the Java language's assert keyword is likely what you want. Under the covers, the assert keyword essentially compiles into Dalvik byte code that does two things:

1. Checks whether the static variable assertionsDisabled (set in the class' static constructor via a call to java.lang.Class.desiredAssertionStatus()) is != 0 and if so, does nothing
2. If it is 0, then it checks the assertion expression and throws a java.lang.AssertionError if the expression resolves to false, effectively terminating your application.

The Dalvik runtime by default has assertions turned off, and therefore desiredAssertionStatus always returns 1 (or more precisely, some non-zero value). This is akin to running in "retail" mode. In order to turn on "debug" mode, you can run the following command against the emulator or the device:

adb shell setprop debug.assert 1

and this should do the trick (should work on the emulator or any rooted debugging-ready device).

Note however that the aforementioned Dalvik code that checks the value of assertionsDisabled and throws an AssertionError if the expression is false is always included in your byte code and liberal sprinkling of asserts in your code may lead to byte code bloat.

Please see this for a bit more detail: Can I use assert on Android devices?

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