Java: Why isn't autoboxing happening here?

问题

This gives me an error:

int[] l = new int[] {0, 2, 192, -1, 3, 9, 2, 2};
int[] l2 = new int[] {9001, 7, 21, 4, -3, 11, 10, 10};
int[] l3 = new int[] {5, 5, 5, 64, 21, 12, 13, 200};

Set<List<Integer>> lists = new HashSet<List<Integer>>();
lists.add(Arrays.asList(l));

Eclipse: The method add(List<Integer>) in the type Set<List<Integer>> is not applicable for the arguments (List<int[]>)

I thought int was supposed to be autoboxed to Integer?

回答1:

Although int is autoboxed to Integer, int[] is not Autoboxed to Integer[].

The arrays are not boxed, just the types themselves.

See this: How to convert int[] into List<Integer> in Java? for workarounds and the underlying reasons.

回答2:

It will autobox from

Integer i = 1
int ii = i;

But, you are trying to convert an array, and when it tries to put an array of primitives as an array of objects they are different.

来源：https://stackoverflow.com/questions/1770894/java-why-isnt-autoboxing-happening-here