/**
* Collection.shuffle的实现 i-1 与 rnd.nextInt(i) 交换
*
* @param arr object[]
*/
public static void shuffle1(Object[] arr) {
int len = arr.length;
for (int i = len; i > 1; i--) swap(arr, i - 1, rnd.nextInt(i));
}
public static void shuffle(Object[] a) {
for (int i = 0; i < a.length; i++) {
swap(a, i, rnd.nextInt(a.length));
}
}