Preview APIs in the Java Platform

[Alex Buckley]

On 3/4/2020 12:10 PM, Ty Young wrote:
>> Especially with Java 14, the entire Java developer community is 
>> becoming aware of the high quality, carefully delivered nature of 
>> preview features in Java SE. If we opened up the mechanism so that API 
>> authors could use it, they would do so -- and each would make slightly 
>> different commitments about quality and readiness. The preview concept 
>> would soon find itself in the same place as the semantic versioning 
>> concept: a simple "standard" for API authors to follow in theory, but 
>> a widely abused and mis-applied concept in practice. We are not going 
>> to take the risk of the preview concept being diluted, because it's 
>> something that every Java developer should recognize and understand 
>> when they peruse the latest "What's new in Java XX" article.
> 
> "slightly different commitments about quality and readiness" is exactly 
> where you are now. String literals have been pulled and modified while 
> other preview features have sailed by with no issues AFAIK.

I have no idea what point is being made here. Raw String Literals (JEP 
326) were going to ship in JDK 12 as a preview feature, but we were 
worried that they didn't meet the completeness bar set out in JEP 12, so 
we didn't ship them in JDK 12. In contrast, Switch Expressions (JEP 325) 
did meet the completeness bar, so we shipped them in JDK 12 as a preview 
feature. We have the same commitment to quality and readiness all day 
every day, which means some features make preview and some don't.

Alex