Share several methods of deduplicating lists through Stream in Java 8

Here I will share several methods for de-duplicating the list. It can be regarded as a sorting. If there are any mistakes, please let me know.

distinct()is a method provided by Stream in Java 8, which returns a stream composed of different elements in the stream. distinct()Use the hashCode()and eqauls()methods to get the different elements. Therefore, classes that need to be deduplicated must implement hashCode()and equals()methods. In other words, we hashCode()can equals()achieve deduplication for some special needs by overriding custom and methods.

distinct()The method declaration is as follows:

Because the Stringclass has overridden the equals()and hashCode()methods , it can be deduplicated successfully.

The result is as follows:

Note: In the code, we use Lombokthe @Dataannotations of the plugin, which can automatically override equals()and hashCode()methods.

The result is as follows:

The result is as follows:

We first create a method as Stream.filter()the parameter of , and its return type is Predicate, the principle is to judge whether an element can be added Setto , the code is as follows:

Use as follows:

The result is as follows:

The above are several methods for list deduplication that I want to share. Of course, there is no more detailed performance analysis here. If there are any mistakes, please let me know.

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