Callable和Supplier的区别

A 

Callable

 is "A task that returns a result, while a 

Supplier

 is "a supplier of results". In other words a 

Callable

 is a way to reference a yet-unrun unit of work, while a 

Supplier

 is a way to reference a yet-unknown value.

It's possible that a 

Callable

 could do very little work and simply return a value. It's also possible a 

Supplier

 could do quite a lot of work (e.g. construct a large data structure). But generally speaking what you care about with either is their principle purpose. For example an 

ExecutorService

 works with 

Callable

s, because it's primary purpose is to execute units of work. A lazy-loaded data store would use a 

Supplier

, because it cares about being supplied a value, without much concern about how much work that might take.

Another way of phrasing the distinction is that a 

Callable

 may have side-effects (e.g. writing to a file), while a 

Supplier

 should generally be side-effect free. The documentation doesn't explicitly mention this (since it's not a requirement), but I'd suggest thinking in those terms. If the work is idempotent use a 

Supplier

, if not use a 

Callable

.

摘自https://softwareengineering.stackexchange.com/questions/254311/what-is-the-difference-between-callablet-and-java-8s-suppliert

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