Closure in Java 7

Question

What is closure  It is supposed to be included in Java 7   Closures were discussed for inclusion in  Java 7  but in the end were not included  -ed  Can anyone please provide me with some reliable references from where I can learn stuff about closures

User · Accepted Answer

Here is Neal Gafter s blog one of the pioneers introducing closures in Java  His post on closures from January 28  2007 is named A Definition of Closures On his blog there is lots of information to get you started as well as videos  An here is an excellent Google talk - Advanced Topics In Programming Languages - Closures For Java with Neal Gafter  as well

User · Answer

A closure is a block of code that can be referenced  and passed around  with access to the variables of the enclosing scope    Since Java 1 1  anonymous inner class have provided this facility in a highly verbose manner  They also have a restriction of only being able to use final  and definitely assigned  local variables   Note  even non-final local variables are in scope  but cannot be used    Java SE 8 is intended to have a more concise version of this for single-method interfaces   called  lambdas   Lambdas have much the same restrictions as anonymous inner classes  although some details vary randomly   Lambdas are being developed under Project Lambda and JSR 335    Originally the design was more flexible allowing Single Abstract Methods  SAM  types  Unfortunately the new design is less flexible  but does attempt to justify allowing implementation within interfaces

User · Answer

Please see this wiki page for definition of closure   And this page for closure in Java 8  http   mail openjdk java net pipermail lambda-dev 2011-September 003936 html  Also look at this Q amp A  Closures in Java 7

User · Answer

According to Tom Hawtin     A closure is a block of code that can be referenced  and passed   around  with access to the variables of the enclosing scope    Now I m trying to emulate the JavaScript closure example on Wikipedia  with a  straigth  translation to Java  in the hope to be useful     ECMAScript var f  g  function foo       var x   0    f   function     return   x       g   function     return --x       x   1    print  inside foo  call to f        f         2      foo    print  call to g        g         1  print  call to f        f         2    Now the java part  Function1 is  Functor  interface with arity 1  one argument    Closure is the class implementing the Function1  a concrete Functor that acts as function  int -  int   In the main   method I just instantiate foo as a Closure object  replicating the calls from the JavaScript example  The IntBox class is just a simple container  it behave like an array of 1 int  int a 1     0    interface Function1         public final IntBag value   new IntBag        public int apply       class Closure implements Function1      private IntBag x   value     Function1 f     Function1 g       Override    public int apply             print  inside foo  call to f        f         2         inside apply  call to f apply          System out println  inside foo  call to f apply        f apply            return 0           public Closure            f   new Function1                 Override            public int apply                     x add 1                   return x get                                  g   new Function1                 Override            public int apply                     x add -1                  return x get                                  x   1         x set 1          public class ClosureTest       public static void main String   args               foo           Closure foo   new Closure            foo apply               print  call to g        g         1          System out println  call to foo g apply        foo g apply                print  call to f        f         2          System out println  call to foo f apply        foo f apply                It prints   inside foo  call to f apply    2 call to foo g apply    1 call to foo f apply    2

User · Answer

Yes Closure  Lambda Expressions  is the new feature with the upcoming Java SE 8 release  You can get more info about this from the below link  http   docs oracle com javase tutorial java javaOO lambdaexpressions html

User · Answer

Java Closures are going to be a part of J2SE 8 and is set to be released by the end of 2012   Java 8 s closures support include the concept of Lambda Expressions  Method Reference  Constructor Reference and the Default Methods   For more information and working examples for this please visit  http   amitrp blogspot in 2012 08 at-first-sight-with-closures-in-java html

User · Answer

A closure implementation for Java 5  6  and 7  http   mseifed blogspot se 2012 09 bringing-closures-to-java-5-6-and-7 html  It contains all one could ask for

[java] Closure in Java 7

Examples related to java

Examples related to closures