Installing

Java

The Android SDK manager has known issues with Java 11. If you have Java 11 installed, you have two not-too-complicated alternatives under Ubuntu: downgrade to Java 8, or upgrade to Java 14 (I chose the latter). They are available through apt as packages openjdk-8-jdk and openjdk-14-jdk (and you should absolutely be running the JDK, not the JRE as gradle will complain about that on building, which can be a pain in the ass).

To choose the right version of Java, run

sudo update-alternatives --config java

and pick your preferred version. Then run java -version just to double-check the version.

Flutter

You can always follow the official guidelines; either way, here are the commands you need to run:

sudo snap install --classic flutter

To check if everything is working properly, run

flutter doctor

to diagnose possible problems, and try to fix them.

Android Studio

Run

sudo snap install --classic android-studio

Then open it, select all default options, and install the Flutter and Dart plugins. Now, restart Android Studio, and create a new Flutter project.

Project

It is possible that you might have to change the gradle version. After doing that, try to compile by selecting “Run” in the upper right corner (you have to select a VM first).

Licenses

If it complains about not having accepted some licenses, open the shell, go to ~/Android/Sdk/tools/bin, run ./sdkmanager --licenses and accept all licenses. Now try to recompile, and it should hopefully (and finally!) work.

If ./sdkmanager --licenses fails (most notably if you’re using Java 14) with message

Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema
	at com.android.repository.api.SchemaModule$SchemaModuleVersion.<init>(SchemaModule.java:156)
	at com.android.repository.api.SchemaModule.<init>(SchemaModule.java:75)
	at com.android.sdklib.repository.AndroidSdkHandler.<clinit>(AndroidSdkHandler.java:81)
	at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:73)
	at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:48)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.annotation.XmlSchema
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:602)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
	... 5 more

then the easiest solution is really to install openjdk-8-jdk, change the current Java version to 8, run ./sdkmanager --licenses and swap again to Java 14. This solution seems pretty dumb, but I find it quite easier than manually changing code you haven’t written, as suggested here.