[TOC]

数组，二维数组，集合

List 与 int[] 与 Integer[]

List<Integer> list = Arrays.asList(1, 3, 2);
Integer[] arr = new Integer[list.size()];
list.toArray(arr);
for(int i=0;i<arr.length;i++) {
    System.out.print(arr[i] + (i==arr.length?"":" "));
}
System.out.println();

int[] arrInt = list.stream().mapToInt(Integer::valueOf).toArray();
for(int i=0;i<arrInt.length;i++) {
    System.out.print(arrInt[i] + (i==arr.length?"":" "));
}
System.out.println();