[Guava official documentation translation] 4. Use Guava Ordering to sort (Ordering Explained)

Source: Internet
Author: User
Tags iterable

assertTrue(byLengthOrdering.reverse().isOrdered(list));

OrderingIs the "smooth version" of Guava"ComparatorIt is used to build advanced comparator and apply comparator to various collections ).

OrderingThe instance is just a special

Ordering

Natural () Natural sorting(Natural ordering ).
UsingToString () The return values of toString () are ordered alphabetically.

However

Ordering<String> byLengthOrdering =  Ordering<String> 

OrderingTo perform some preprocessing. Some of the most common solutions are as follows:

Reverse ()
NullsFirst () OrderingPlace the null element before the non-null element.Ordering is the same.The same is true for nullsLast.
Compound (Comparator) OrderingUse the specifiedComparatorSort again.
Lexicographical () OrderingThe iterable elements are ordered alphabetically.
OnResultOf (Function) OrderingPass the sorted elements into the function and use the originalOrdering sorting.

 


 

Processing null values based on sortedBy. The following is a solution for application chain call:

 

Ordering<Foo> ordering = Ordering.natural().nullsFirst().onResultOf(newFunction<Foo,String>

 

 In Ordering.

The chain call of compound should be viewed from left to right. To avoid confusion, do not CompoundMixed processing of calls and other chained calls .)

Ordering<Foo> ordering = Ordering.natural().nullsFirst().onResultOf(sortKeyFunction);

GreatestOf (Iterable iterable, int k) LeastOf
IsOrdered (Iterable) IterableWhether or not the ordering sorting rules are ordered (monotonic non-subtraction ). IsStrictlyOrdered
SortedCopy (Iterable)
ImmutableSortedCopy
Min (E, E) Max (E, E)
Min (E, E ...) The smallest of the two parameters is returned Based on the ordering sorting rule. If there are multiple equal minimum values, the first value is returned.
Max (E, E ...)
Min (Iterable) The minimum Iterable value. IfThisIterableIf it is null, return Max (Iterable),Min (Iterator),Max (Iterator)

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