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Support for standard library polyfills

See original GitHub issue

I really like the idea behind this project. What the frontpage does not mention, is that a valid Java 8 bytecode can’t still have a hard time running on actual JRE8 because of missing pieces of the standard library like List.of().

So the idea is that the plugin could somehow rewrite references of java.util.List#of() to a different static method in a specially created polyfill library.

What do you think?

Issue Analytics

  • State:open
  • Created 4 years ago
  • Reactions:1
  • Comments:5 (2 by maintainers)

github_iconTop GitHub Comments

bsideupcommented, Sep 1, 2019

It also worth mentioning that the language features enabled by Jabel do not require any new stdlib methods btw

tlinkowskicommented, Oct 7, 2019

Hi, you might be interested in UniJ, which provides a backport of JDK 9+ APIs in the form of a facade.

E.g. UniLists.of(1, 2) corresponds to List.of(1, 2). At runtime, it delegates to:

  • either List.of(1, 2) (for JDK 9+)
  • or Collections.unmodifiableList(Arrays.asList(1, 2)) (for JDK 8)


  • you added a dependency on UniJ
  • and Jabel could rewrite List.of references into UniLists.of ones

you’d achieve the effect you want.

Instance methods (like would be much more problematic to rewrite, though.

Disclaimer: I’m the author of UniJ.

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