是否有一个JDK或guava方法将null转换为空列表 [英] Is there a JDK or guava method to turn a null into an empty list

问题描述

在JDK或Google guava中有这样的方法

Is there a method like this one in the JDK or Google guava

public static <T> Collection<T> safe(Collection<T> collection)
{
    if (collection == null)
    {
        return new ArrayList<>(0);
    } else
    {
        return collection;
    }
}

例如

   for (String string : CollectionUtils.safe(foo.canReturnANullListOfStrings()))
   {
      // do something
   }

不会崩溃。

我环顾四周，但找不到任何这样的方法，我想知道如果我错过了，或者有一个原因，为什么这种方便的方法不方便，因此不包括？

I looked around but could not find any such method, and I am wondering if I missed it or if there is a reason why such a handy method is not handy and therefore not included?

推荐答案

Objects.firstNonNull(list, ImmutableList.<Foo>of());

不需要一个专门的方法，这的确是的解决方案，我们建议你立即使用，只要你从一个淘气的API得到一个潜在的null集合，理想情况下不应该首先这样做。

There's no need for a specialized method, and this is indeed the solution we recommend you use immediately whenever you get a potentially-null collection from a naughty API that ideally shouldn't do that in the first place.

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