什么传递给Arrays实例方法toArray（T [] a）方法？ [英] What to pass to the Arrays instance method toArray(T[] a) method?

问题描述

如果您有集合的实例，请说：

If you have an instance of a Collection, say something like:

Collection<String> addresses = new ArrayList<String>();

然后填充一堆值，这是最好的方式，if

Which were to then be populated with a bunch of values, which is the "best" way, if any, to make use of the toArray() method without requiring a type cast?

String[] addressesArray = addresses.toArray(new String[] {});
String[] addressesArray = addresses.toArray(new String[0]);
String[] addressesArray = addresses.toArray(new String[addresses.size()]);
String[] addressesArray = addresses.toArray(new String[addresses.size() + 5]);

前两者之间有语义上的区别吗？是第三最有效吗？是第四个比第三个效率低吗？

Is there any semantic difference between the first two? Is the third most efficient? Is the fourth less efficient than the third?

推荐答案

根据 findbugs报告，这是最有效的：

String[] addressesArray = addresses.toArray(new String[addresses.size()]);

我相信他们;）

这篇关于什么传递给Arrays实例方法toArray（T [] a）方法？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！