二分法查找数组中的元素并返回其对应的索引

package org.westos.homework;/** * 现要求采用二分法找出指定的数值并将其在数组的索引返回，如果没有找到则返回 -1 */import java.util.Arrays;public class HomeWork02 {public static int search(int[] arr,int key) {Arrays.sort(arr);//System.out.println(Arrays.toString(arr));int start = 0;int end = arr.length-1;while(start <= end) {intmiddle = (start + end)/2;if(key < arr[middle]) {end = middle-1;}else if(key > arr[middle]) {start = middle+1;}else{return middle;}}return -1;}public static void main(String[] args) {int [] arr = {80,40,50,45,90,120,30,20,100};System.out.println(search(arr, 40));System.out.println(search(arr, 30));System.out.println(search(arr, 100));}} 运行结果：