Why would Google bother keeping the JVM class hierarchy if they were implementing a different VM to run against anyway? That just seems to be asking for trouble. I can sort of see some merit to Oracle's argument now. It would be one thing if JVM byte code was treated as an Intermediary representation that then compiled to Dalvik... but it isn't even really that.
Damn, Google stepped in it. Hard.
Edit: Further research indicates Java Byte code is an intermediate representation compiled to Dalvik; so technically the Java Hello World would work coming out in Dalvik (or Android Runtime). So... Back to being confused again, because clearly, even if Google did copy pasta the Java APIs the end machine they are driving is drastically different; I.e., System.out.println() would generate no visible output on Android.
So I'm really back in Google's camp, Oracle is trying to copyright a steering wheel.
Oracle wants patent like protections for the output of Java, and overall API structure in all languages. They want copyright on a meta-pattern. Just trying to imply skulduggery to "look, they joined our API structure, and didn't even do a good job of it, so they should have to pay us for infringement" is a transparent farce. It's an entrenching power grab.
There's a whole section in that opinion I linked above titled, "Google's Interoperability Arguments are Irrelevant to Copyrightability," that's worth reading for a deeper treatment of the issue. In particular, Judge O'Malley (quite reasonably) calls bullshit on the very premise that Google copied the Java APIs in order to achieve interoperability, pointing out that Google did specific things to prevent such interoperability (as an aside, we now know that their desire to do so, and Sun's unwillingness to agree to that, is a major reason why they could not come to terms on a licensing agreement), and was unable to produce any examples of a pre-existing Java program that also runs on Android.