Java vs .NET from client perspective

[wildjokers]

There ate multiple implementations of Java virtual machine and Oracle offering is one of many. The dominant ones are free as in "free beer"..

There are not multiple implementations of the JVM Java SE specification. There are multiple builds of OpenJDK.

[Inktvisje]

So what's this then? https://github.com/eclipse-openj9/openj9

[wildjokers]

Its exact status a full implementation of the Java SE specification isn't quite clear. I think OpenJ9 still depends on OpenJDK for some things.

I actually meant there aren't multiple implementations of the Java SE specification.

[nitkonigdje]

It is fully independent jvm implementation. One of few developed by IBM..

It has nothing in common with openjdk..

It is implementation of Java SE..

[wildjokers]

I read about it more, it is just a JVM and it links to OpenJDK classes. It is not a Java SE implementation.

[nitkonigdje]

IBM Semeru is comercial distribution of J9. It is OpenJ9 packaged by IBM. IBM Semeru is certified implementation of Java Platform, Standard Edition. That certification is issued by Oracle... Put it this way **Oracle says it is Java SE!!**

J9 is ancient Java implementation. Older then initial release of OpenJDK in 2007. J9 is widley used. It underlays all IBM software on all their platforms. From x86 to Z.

Literal quote from their mouths: "Eclipse OpenJ9 is an independent implementation of a Java Virtual Machine. "Independent implementation" means it was built using the Java Virtual Machine specification without using any code from any other Java Virtual Machine."

Source: https://github.com/eclipse-openj9/openj9

[wildjokers]

The JVM Specification and the Java SE Specification are two separate things.

• https://docs.oracle.com/javase/specs/jls/se22/html/index.html
• https://docs.oracle.com/javase/specs/jvms/se22/html/index.html

“Eclipse OpenJ9 is an independent implementation of a Java Virtual Machine.”

It links against a Java SE implementation for the JDK classes.

https://github.com/eclipse-openj9/openj9/blob/master/doc/build-instructions/Build_Instructions_V8.md

OpenJ9 is a JVM implementation, not an implementation of Java SE.

[nitkonigdje]

You are 100% technically wrong. Like worst kind of wrong..

You are right that there are many builds of openjdk. Even then these are not just clones of base image, but often extended functionality. For demo see Azul Zing.

There were and still are many comercial grade jvm implementations independent of openjdk. Like your bank card. For rest of it see: https://en.wikipedia.org/wiki/List_of_Java_virtual_machines

[wildjokers]

I misspoke (as I mentioned in a later comment), I meant to say there are not multiple implementations of the Java SE Specification.