如何转换Set< String>到String []？
问题描述：
我需要从 Set< String> 中获取 String [] ，但我不知道知道怎么做。以下操作失败：
I need to get a String[] out of a Set<String>, but I don't know how to do it. The following fails:
Map<String, ?> myMap = gpxlist.getAll();
Set<String> myset = myMap.keySet();
String[] GPXFILES1 = (String[]) myset.toArray(); // Here it fails.
如何修复它以使其有效？
How can I fix it so that it works?
答
使用 设置#toArray（T []） 方法获取相同大小的类型数组参数。
Use the Set#toArray(T[]) method taking a typed array argument of the same size.
String[] GPXFILES1 = myset.toArray(new String[myset.size()]);
也可以使用不同的大小，但这会强制 toArray（ ）创建一个新数组以返回而不是重用提供的参数的方法，这可能最终效率较低。
A different size can also be used, but that would force the toArray() method to create a new array to return instead of reusing the provided argument, which may end up to be less efficient.