什么要传递给数组实例方法的toArray（T [] a）方法？ [英] What to pass to the Arrays instance method toArray(T[] a) method?

问题描述

如果你有一个集合的实例，这样说：

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

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

这当中，然后被一帮价值观，这是最好的方式，如果有的话，尽量使用toArray（）方法，而不需要一个类型转换填充？

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]);

有没有前两者之间的语义差别？是第三个最有效的？是第四个比第三低效率？

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

根据一个FindBugs的报告，这是最有效的：

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

我相信他们;）

这篇关于什么要传递给数组实例方法的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！