Why did Google choose Java for the Android Operating System and not some other language?

I have revisited this question 9 years later. I realize that this question invites a lot of debate and personal opinion. I want to try to and reframe this question if possible, so we keep personal opinions and preference out of it.

Why Java specifically? Was it because of technical merits? Was it because so many developers know Java? Was it because Java was actually the best **garbage-collected** language at the time? Or was it because that is what the initial developers chose and they had to stick with it once the project got officially picked up?

I know that there are more *modern* languages available today then there were in 2008, when Android was first released. I don't know though how many viable alternatives to Java Google had in 2008. And I don't know much about the Java ecosystem, as I'm not a Java developer. Was Java the best available open source alternative back then? Was it a good option because Sun was still developing it back then?

These are the kind of considerations I wanted to know about. Environmental constraints, technical constraints, etc. And I don't mean which language is better. I mean which language could have fit their needs better and why in the end they chose Java?