Debugging Android Projects

You can use Android Studio to debug the C++ and Java code used in your Unreal Engine (UE) projects. This tutorial will guide you on how to set up Android Studio for this process.

Reduce Iteration Times

To reduce the build time for Android projects during iteration, you can set your project to avoid bundling libUnreal.so in your .apk and instead push it to an internal file directory on your device. This skips gradle and avoids reinstalling the .apk with every change. To implement this, open your project's *Engine.ini and add the following lines to it:

*Engine.ini

	[[/Script/AndroidRuntimeSettings.AndroidRuntimeSettings]
	bDontBundleLibrariesInAPK=True
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[[/Script/AndroidRuntimeSettings.AndroidRuntimeSettings] bDontBundleLibrariesInAPK=True

If you are using Unreal Build Tool directly, you can also pass -ForceDontBundleLibrariesInAPK=true to enable this setting.

After you opt in to this setting, it should be enabled for both AGDE and Quick Launch for non-shipping builds. Shipping builds still bundle libUnreal.so in your .apk.

Set Up Android Studio

To set up Android Studio to debug a UE project, follow these steps:

1. If you have not already done so, download and install the version of Android Studio that is compatible with your current build of Unreal Engine. Refer to the Development Requirements page for information on which version to use, and the Android SDK and NDK Setup guide for information about how to set up your environment.

2. Build the APK that you want to debug and then deploy it to your Android device you will be using for debugging.

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3. Open the Android Studio Launcher and from the displayed options, then select the Open an existing Android Studio Project.

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4. From the Open File or Project menu, navigate to C:\YourProjectName\Intermediate\Android\APK\Gradle and select the Gradle directory, then press the OK button.

   

5. Once Android Studio is open, go to the Run Menu and select the Edit Configurations option.

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6. Click on the Debugger tab and set the debug type to Dual.

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7. Next, go to the LLDB Startup Command tab, press plus icon (+) and then input the following line, pressing the OK button to complete the process.

       command script import "C:\PathToYourUE4EngineInstall\Engine\Extras/LLDBDataFormatters\UE4DataFormatters_2ByteChars.py"
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   command script import "C:\PathToYourUE4EngineInstall\Engine\Extras/LLDBDataFormatters\UE4DataFormatters_2ByteChars.py"

   Note that TEXT("string") should be used instead of L("string") in your C++ code.

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   Make sure to press the Enter key or the command will not take.

8. Now, open up any of your project's .cpp files and add breakpoints to items you want to debug.

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9. From the main menu, select Run > Debug 'app-app'.

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1. When the Select Deployment Type windows is displayed, select your device from the list and press the OK button.

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End Result

Once you have completed the above steps, wait for the debugger to attach to your Android Device.

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Depending on the size of your project, it could take some time for the debugger to attach. This also does not install the data on the device if you don't use the Package data inside APK option. Doing so will make the redeploying for debugging slower since the APK will be larger. Another option is to first do a Launch on in the editor before using Android Studio for debugging to install the current level on the device. Alternatively, you can package and install the OBB on the device if you need more than the current level data.