Java 8 frequency Object in array [duplicate]

问题

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Word frequency count Java 8 (8 answers)

Closed 4 years ago.

I have an Object[] array

I need to create map Map<Obejct, Integer>, where Integer value contains frequency of key Object in array.

How can i do it in java 8 style, using Collectors?

回答1:

You can do (I hope I don't have any typos) :

Map<Object,Long> map = Stream.of(array)
                                .collect(Collectors.groupingBy(o -> o,
                                                               Collectors.counting()));

This should group the elements of the array by equality and count the number of Objects in each group.

来源：https://stackoverflow.com/questions/29450169/java-8-frequency-object-in-array