Running Java bytecode on the Android - Sun JVM on top of DalvikVM

Question

Since both the java implementation (OpenJDK) and Android\'s virtual machine DalvikVM are opensource it must be possible to implement Sun\'s JavaVM on top Google\'s

Answer 1

The OpenJDK makes use of native code so it would be a non-trivial port... there is at least one VM (JikesRVM) that is written in Java, unfortunately it is not a completely working implementation of Java.

Since DalvikVM runs classes that were converted from .class files it should be possible to convert the classes over. Then the "only" issue is when languages generate bytecode on the fly - for that it would require the extra step of converting the generated bytecode over to the DalvikVM format while the program is running on the DalvikVM.

Hmmm.... sort of a JITT (Just In Time Translator) that covertes class files to a DalvikVM files at runtime on the phone. I wonder how slow that would be.

Answer 2

I don't think the problem is technical. In theory you can migrate OpenJDK to the iPhone for example, but there are legal restriction in place.

Answer 3

See http://davy.preuveneers.be/phoneme/ for MIDP, Foundation and Personal Profile jvms for Android ARM apks. (Thank you Davy!!!)

I have repackaged the Foundation jvm for command line use and host it at vkfox.com/android/bin/foundation-jvm.bin for your pleasure. One could use the eclipse compiler in the JavaIDEdroid free app, or the old kopi or kopisusu compilers with this jvm, togeather with the stubbed cdc + foundation jar file from a J2ME jdk for an onboard development system. Using the features of TerminalIDE -- console and sun compiler -- with indicated ref jars would also get you there. This is essentially equivalent to a headless jdk1.4 with the possibility of MIDP or awt graphics.

Answer 4

technically it should be possible to interpret hotspot byte-code on dalvik vm or dalvik's byte-code on hotspot, but it will never be efficient (not mentioning elegant) design for a long run. the cost of doing that might become very high especially with respect to maintenance in the future evolution of such a split ecosystem.

i think, from the very beginning, dalvik vm is a matter of power/market control rather than innovative effort to improve java virtual machine ecosystem. dalvik vm and hotspot vm are lake two highway bridges across the same river build in parallel five meters from each other. it divides and brings confusion to java technological ecosystem.

google is, in my opinion, definitely the technological leader with innovative contributions over last decade that dwarf far more conservative oracle, but in this very subject they have shaken the java ecosystem in nearly destructive way. we (programmers) should strive for a single uniform solution to this problem. that is the main idea behind the concept of "virtual machine" anyway - it should not belong to neither google nor oracle.

Answer 5

try GNURoot app (proot ptrace container) with debian Wheezy;
apt-get update
apt-get install openjdk-7-jre
/usr/lib/jvm/java-7-openjdk-armel/jre/bin/java ...
(including long path)

Answer 6

In the meantime I have found a possible solution (only JavaME):

• "MicroEmulator is a pure Java implementation of Java ME in Java SE."
• Running Java ME applications on Android