二分查找

public static void main(String[] args) {int[] num = {6,5,9,8,45,2,3,55,1};Arrays.sort(num);//升序排序int left = 0;//左边开始int right = num.length;//右边开始int key = 55;//要查找的int middle = 0;//中间值while(true){middle = (left+right)/2;if(key==num[middle]){break;}else if(key>num[middle]){left = middle+1;}else if(key<num[middle]){right = middle-1;}}System.out.println(middle);//排序后key的下标}