JavaArchiveDownloadEvent

Gets fired while a Java runtime archive is being downloaded.

Fields

progressdouble

The overall download progress as a value from 0.0 to 1.0

downloadedByteslong

The number of bytes downloaded so far.

totalByteslong

The total size of the Java archive in bytes.

downloadUrlString

The URL the Java archive is being downloaded from.

When it fires

This only fires when EnsureJavaVersionEvent also fired (your JVM is too old) and no already-extracted managed runtime exists yet on disk for the required major version/platform combination. If Minified previously downloaded and extracted a matching runtime, it’s reused directly and this event doesn’t fire at all. The archive itself is always downloaded fresh into a temporary file (deleted again after extraction) - it’s the extracted runtime, not the archive, that’s cached between launches. It’s fetched from Eclipse Adoptium (api.adoptium.net).

Progress is throttled to roughly one event per 100ms while bytes are streamed in, followed by a guaranteed final event at progress: 1.0 so listeners always see completion even if the download finishes between throttle windows. If the server doesn’t report a Content-Length header, progress is reported as -1.0 for every event except the final one - fall back to showing downloadedBytes as a raw counter in that case.

After this event stops firing, the checksum of the downloaded archive is verified against Adoptium’s metadata before extraction begins (see ExtractArchiveEvent). A checksum mismatch throws an IOException and no extraction event fires.

Posted to the EventBus given to JavaManager.init(...) - see the note on EnsureJavaVersionEvent.