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Re: Lambda reference?

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On 3/14/2016 5:16 PM, Eric Sosman wrote:
> On 3/14/2016 4:32 PM, Rhino wrote:
>> I'm just new to Java Lambda expressions. I'm both excited and frustrated
>> by the Oracle tutorials describing them: the tutorial shows how powerful
>> they are and that's got me keen to know more but I'm not finding the
>> detailed references I need to be able to do what I want to do.
>> [...]
>
>      See Sebastian's response.  I'd just like to add that lambdas and
> streams are two different things, and that you may confuse yourself
> if you try to conflate them.  Lambda expressions are often useful with
> streams, but you can use streams without them.  Streams are frequent
> users of lambda expressions, but lambda expressions have non-stream
> uses as well.
>
>      Here's a fragment using a lambda, with no stream (or collection)
> anywhere in sight:
>
>      gadget.addActionListener((evt) -> {
>          ... do something with the ActionEvent ...
>      });
>
> ... which we used to have to write as:
>
>      gadget.addActionListener(new ActionListener() {
>          @Override
>          public void actionPerformed(ActionEvent evt) {
>              ... do something with the ActionEvent ...
>          }
>      });
>
>      And here's a stream operation with no lambda in the neighborhood:
>
>      Predicate<Thing> pred = new Predicate<>() {
>          @Override
>          public boolean test(Thing thing) {
>              ... long, complicated computation ...
>              return answer;
>          }
>      };
>      List<Thing> theChosenFew = allThings.stream()
>          .filter(pred)
>          .collect(Collectors.toList());
>
> ... which we might have lambda-ized (if it's not too bulky):
>
>      List<Thing> theChosenFew = allThings.stream()
>          .filter((thing) -> {
>              ... long, complicated computation ...
>              return answer;
>          })
>          .collect(Collectors.toList());
>
>      So: Although they are frequently used together, try to bear in
> mind that there's no "necessary" connection between lambda expressions
> and stream operations.
>
Excellent point! I've just come across lambdas for the first time in a 
tutorial on collections so I'm sure I *am* conflating them somewhat. 
I'll make sure to treat them as separate and distinct things that may be 
useful to one another.



-- 
Rhino

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Lambda reference? Rhino <no_offline_contact@example.com> - 2016-03-14 16:32 -0400
  Re: Lambda reference? Sebastian <news@seyweiler.dyndns.org> - 2016-03-14 21:50 +0100
  Re: Lambda reference? Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-03-14 17:16 -0400
    Re: Lambda reference? Rhino <no_offline_contact@example.com> - 2016-03-14 18:29 -0400
    Re: Lambda reference? Eric Douglas <e.d.programmer@gmail.com> - 2016-03-16 04:53 -0700
      Re: Lambda reference? Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-03-16 08:38 -0400
        Re: Lambda reference? Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-03-16 08:45 -0400
          Re: Lambda reference? Sebastian <news@seyweiler.dyndns.org> - 2016-03-16 21:33 +0100
          Re: Lambda reference? Robert Klemme <shortcutter@googlemail.com> - 2016-03-25 18:35 +0100
            Re: Lambda reference? Eric Douglas <e.d.programmer@gmail.com> - 2016-03-28 07:06 -0700
              Re: Lambda reference? Robert Klemme <shortcutter@googlemail.com> - 2016-03-31 00:09 +0200
                Re: Lambda reference? Eric Douglas <e.d.programmer@gmail.com> - 2016-03-31 04:42 -0700
                Re: Lambda reference? Robert Klemme <shortcutter@googlemail.com> - 2016-03-31 18:35 +0200
                Re: Lambda reference? Eric Douglas <e.d.programmer@gmail.com> - 2016-03-31 11:21 -0700
  Re: Lambda reference? Rhino <no_offline_contact@example.com> - 2016-03-14 21:55 -0400

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