Closures in Java 7 [duplicate]

Question

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• Closure in Java 7 [closed] 7 answers

I have heard that closures could be introduced in the next Java standard that is scheduled to be released somewhere around next summer.

What would this syntax look like?

I read somewhere that introducing closures in java is a bigger change than generic was in java 5. Is this true? pros and cons?

(By now we definitely know that closures not will be included in the next Java release)

OR

edit: http://puredanger.com/tech/2009/11/18/closures-after-all/ :D

edit2: Re-thinking JDK7: http://blogs.oracle.com/mr/entry/rethinking_jdk7

edit3: There’s not a moment to lose!: http://blogs.oracle.com/mr/entry/quartet

Answer 1

Unofortunately you will not find closure in Java 7. If you are looking for a lighter solution to have closure in java just now check out the lambdaj project:

http://code.google.com/p/lambdaj/

Answer 2

It really depends on what gets introduced, and indeed whether it will be introduced at all. There are a number of closure proposals of varying sizes.

See Alex Miller's Java 7 page for the proposals and various blog posts.

Personally I'd love to see closures - they're beautiful and incredibly helpful - but I fear that some of the proposals are pretty hairy.

Answer 3

Note that a "function-type" is really a type under the proposal:

{int => boolean} evaluateInt;    //declare variable of "function" type
evaluateInt = {int x => x % 2 }; //assignment

Answer 4

This is the java 7 features http://tech.puredanger.com/java7/#switch the examples are very usefull.

Answer 5

closures will be annoyinglly verbose if there won't be any sort of type inference... :(

Answer 6

Closures have some serious edge cases. I would say that Closures are a much more significant change than Generics and the later still has a number hairy edge cases. e.g. The Java Collections libraries cannot be written/compiled without warnings.