从小到大排序
for (int j = 2; j < arr.length; j++) {
int key = arr[j];int i = j - 1;
while (i > 0 && arr[i] > key) {
arr[i + 1] = arr[i];
i--;
}
从大到小排序
for (int j = 1; j < arr.length; j++) {
int key = arr[j];
int i = j - 1;
while (i >= 0 && arr[i] < key) {
arr[i + 1] = arr[i];
i--;
}
arr[i + 1] = key;
}