检查集合是否包含对象，通过引用进行比较

问题描述

方法检查集合是否包含给定对象，使用 c>等于（） li>

我不想更改集合中的对象和集合本身。

strong>编辑：

尽管我的问题是关于

解决方案

对于集合子接口我们使用Java 8，是一个干净的选项：

  collection.stream anyMatch（x-> x == key）
  

The Collection.contains() method check if a collection contains a given object, using the .equals() method to perform the comparison.

From Java7 Javadoc:

Is there a smart way to check if a collection contains an object o, but comparing by reference instead (i.e. o==e)?

Of course I can iterate through the collection and make the check, I'm looking for an existing function which can do that.

Clarifications:

• I want to perform this operation regardless the equals() implementation of the object in the collection.
• I don't want to change the objects in the collection nor the collection itself.

Edit:

Even though my question is about a general solution for Collection implementations, specific cases for Collection sub-interfaces would also be appreciated.

解决方案

For those of us using Java 8, Collection#stream() is a clean option:

collection.stream().anyMatch(x -> x == key)

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