对于集合中包装的对象实用方法 [英] Utility method for wrapping an object in a collection

问题描述

我正在寻找在Java核心类库的静态方法或其他一些常用的依赖 - $ P $的Apache pferably一员 - 执行以下操作：

I'm looking for a static method in the Java core libraries or some other commonly used dependency — preferably one of Apache — that does the following:

public static <T> Collection<T> wrap(final T object){
    final Collection<T> collection = new ArrayList<T>();
    collection.add(object);
    return collection;
}

你知道这样的方法已经存在？因为我想这个问题是共同的，我不想重复它的解决方案。

Do you know where such a method already exists? Since I guess the problem is common, I don't want to duplicate it's solution.

推荐答案

java.util.Collections.singleton（对象）会给你一个不变设置。 singletonList 也是可用的。

java.util.Collections.singleton(object) will give you an immutable Set. singletonList is also available.

效率较低 java.util.Arrays.asList（对象）会给你一个可变的（可以使用 list.set（0，X） ; ），但非结构性改变的（不能添加或删除）列表。这是一个有点贵，因为是创建客户端一个额外的数组。

Less efficiently java.util.Arrays.asList(object) will give you a mutable (can use list.set(0, x);), but non-structurally changeable (can't add or remove) List. It is a bit more expensive as there is an extra array that is created client-side.

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