Preview APIs in the Java Platform

[Alex Buckley]

On 3/6/2020 5:23 AM, Volker Simonis wrote:
> There's one major difference between the "Preview" and the "Incubator"
> approach which doesn't seemed to have been covered in this thread.

Of course you're right that preview APIs (and preview features more 
broadly) are part of Java SE, while incubating APIs are "just" a 
JDK-specific API in a JDK-specific module.

The reason we compare them directly is because both represent a channel 
to the same thing: a complete, stable, high-quality API in Java SE.

The point I took from Chris's mail is that if an API is good enough to 
be considered for incubation, then it's probably not very far away from 
being ready to preview. (Incubation was never about allowing half-baked 
APIs out into the world -- there was every expectation of good quality 
regardless of the non-SE status, though no guarantee of stability.) In 
theory, you could incubate an API for a few releases and then preview, 
but there's an explanation tax if you do that, so in reality, it's more 
efficient to hang back and offer Project-specific EA binaries (the true 
"lightweight" approach to introducing new APIs) until you're ready to 
preview.

Alex