lambda binary snapshots

[Brian Goetz]

in general, keep in mind that the library work is all completely speculative and may look nothing like the final product.  

Composing comparators allows you to impose a dictionary ordering.  So:

  Comparator<Person> byLastName = comparing(Person::getLastName);

  Comparator<Person> byLastAndFirstName = byLastName.compose(comparing(Person::getFirstName));

The second of these will compare by last and first name, that is, when last name is equal, it will resolve ties by comparing first name.  

Because this is an extension method, the receiver in the invocation becomes the first argument to the default:  

  foo.compose(bar)

becomes

  compose(foo, bar)

when it is actually executed.



On Nov 13, 2011, at 1:52 AM, Arul Dhesiaseelan wrote:

> JDK 8 Lambda build is cool. Thanks for making this available!
> 
> I was playing with defender methods, wondering what makes this scenario
> work:
> 
> In Comparator, there is a new default method compose() which has single
> parameter:
> 
> Comparator<T> compose(Comparator<? super T> other) default
> Comparators.compose;
> 
> The default implementation in Comparators has two parameters:
> 
> public static<T> Comparator<T> compose(Comparator<T> first, Comparator<?
> super T> second) {}
> 
> For example, the woven class String.CASE_INSENSITIVE_ORDER
> (CaseInsensitiveComparator.class) has single parameter. I am not sure I
> understand how this works, need help.
> 
> -Arul
>