When installing Android Studio, a Java environment is installed along with it. When configuring Creator to use that by going to:

Tools -> Options... -> Devices -> Android tab -> JDK location

and pointing it to:

/opt/android-studio/jre

the location is recognized and everything works as expected. Except for the AVD Manager tab. The list where AVDs would normally appear is empty and thus the emulator cannot be started.

For this to work, I have to manually start Creator from the command line using:

JAVA_HOME=/opt/android-studio/jre /path/to/qtcreator

The AVDs then appear and can be started.

Given that Creator already knows the path to the JAVA installation, setting JAVA_HOME manually should not be necessary.