CheerpJ 4.2 Released: Better Java 17 Support and Clipboard Fixes

CheerpJ 4.2 improves Java 17 support in the browser and fixes clipboard handling, with bug fixes across the runtime.

Stefano De Rossi

26 June 2025

CheerpJ 4.2 is now available. It is a maintenance release that follows CheerpJ 4.1, and it builds on the feedback we received on the Java 17 preview.

What’s new in CheerpJ 4.2

Improved Java 17 support. The Java 17 preview introduced in CheerpJ 4.1 has been tested on many more applications and libraries, and this release fixes the issues that testing found.
Clipboard fixes. Several fixes make copy and paste between Java applications and the rest of the page more reliable.
Bug fixes. Various fixes across the runtime.

Upgrading is a matter of changing the version in the loader URL:

<script src="https://cjrtnc.leaningtech.com/4.2/loader.js"></script>

The changelog lists every change, and the documentation has guides, examples and tutorials.

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