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i would like to update from Oracle Java to Adopt OpenJDK. Therefore i have some question before i start doing the update:

Some information about the application i use:

  1. 2 applications
  2. Application 1 uses Java 8
  3. Application 2 uses Java 11

My Questions:

  1. Are there any known problems updating from oracle Java 8 to AdoptOpenJDK 8?
  2. Are there any known problems updating from oracle Java 11 to Adopt OpenJDK 11?
  3. Is it even possible to run a Java 8 Application on Java 11? (Can i use Adopt OpenJDK 11 for both applications?)
  4. Is there any guideline to update from Oracle to Adopt? (Or just straigt forward?)

best regards

Jon Heller
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Mico61
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1 Answers1

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For a given Java version (since Java 8), the various commercially-supported OpenJDK builds are almost drop-in replacements for the Oracle JDK.

If you're writing an application with a GUI, you'll find some differences in the fonts, and in colour profiles. The Oracle JDKs also have better support for Java Flight Recorder (if anybody uses that). There's little support in OpenJDK for the ancient Java Web Start, but there are alternatives.

In my experience (which is nearly all in middleware), choice of JDK (for a given version) is almost always a decision about support, and rarely about features. I've rarely encountered any technical problems moving from Oracle JDK to OpenJDK, or vice versa.

I've also not found any problems running Java 8 applications with Java 11 and later. However, Java 11 decoupled several components -- again most related to GUI applications -- into separate JARs.

But, in the end, this is all a matter of testing, isn't it? If your testing is sufficiently thorough, any problems with compatibility will be flushed out. I certainly wouldn't rely on anybody else's claims of backward compatibility without thorough testing.

Kevin Boone
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  • Thank you very much for your answer. Do i have to pay attention to something, before i start switching from Oracle Java to Adopt OpenJDK? – Mico61 Sep 22 '20 at 11:45
  • Switching JVMs is usually easy. Provided you aren't working in a live, production environment, just do it, and see what happens. – Kevin Boone Sep 22 '20 at 11:49