import java.util.*;
public class Solution {
    public int search (int[] nums, int target) {
        int l = 0;
        int r = nums.length - 1;
        //从数组首尾开始,直到二者相遇 fast-template
        while(l <= r){
            //每次检查中点的值
            int m = (l + r) / 2;
            if(nums[m] == target)
                return m;
            //进入左的区间
            if(nums[m] > target)
                r = m - 1;
            //进入右区间
            else
                l = m + 1;
        }
        //未找到
        return -1;
    }
}

优化

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
     *
     * 
     * @param nums int整型一维数组 
     * @param target int整型 
     * @return int整型
     */
    public int search (int[] nums, int target) {
        // write code here
        int left=0; 
        int right=nums.length-1;
        while(left<=right){
            int mid=left+((right-left)>>1);//防止相加超出int范围
            if(nums[mid]==target){
                return mid;
            }else if(target<nums[mid]){
                right=mid-1;
            }else{
                left=mid+1;
            }
        }

        return -1;
    }
}