Java中的二分法

int[] ages = {12, 14, 15, 16, 19, 20, 21};
int low = 0;
int height = ages.length - 1;

int key = 20;
while (low <= height) {
    int middle = (low + height) / 2;
    if (ages[middle] == key) {
        System.out.println("找到了" + ages[middle] + "=====" + middle);
        return;
    }
    if (ages[middle] < key) {
        low = middle + 1;
    } else {
        height = middle - 1;
    }
}
System.out.println("not found..");