Array.binarySearch返回错误的数据 [英] Array.binarySearch returning wrong data

问题描述

我想验证用户名和密码使用数组和array.BinarySearch功能。数组中的前两个用户名：布拉德利和约翰正在使用的功能0和1返回正确的位置，但是当我尝试验证数组吉姆和克拉克最后两个字符串的函数的binarySearch返回的用户名位于位置-2两次数组，这是造成验证失败英寸任何想法？

 的String [] =名称{布拉德利，约翰，吉姆，克拉克};
    的String [] =密码{密码，密码，测试，测试};
    INT POS = Arrays.binarySearch（姓名，UNAME）;
                    的System.out.println（发现你的数组：+ +的uname的位置：+ POS）
                    如果（POS＆GT; = 0）
                    {
                        的System.out.println（用于验证口令：+的uname）;
                        如果（密码[POS] .equals（PWORD）及和放大器;！loggedOn [POS]）
                        {
    }
 

解决方案

您名称数组没有排序：

 的String [] =名称{布拉德利，约翰，吉姆，克拉克};
 

这是<一个要求href=\"http://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html#binarySearch%28java.lang.Object%5b%5d,%20java.lang.Object%29\"相对=nofollow> 的binarySearch（） （和的二进制搜索算法）：

  

的范围必须升序排序

第一个排序它，它就会像一个魅力：

 的String [] =名称{布拉德利，克拉克，吉姆，约翰};
 

I am trying to validate password and username using array and the array.BinarySearch function. The first two user names in the array: bradley and john are returning the correct position using the function 0 and 1. However when I try to validate the last two strings in the array jim and clarke, the binarySearch function returns the username is located at position -2 in the array both times which is causing validation to fail. Any ideas?

 String[] names = {"bradley","john","jim","clarke"};
    String[] passwords = {"password","password","test","test"};
    int pos = Arrays.binarySearch(names, uname);
                    System.out.println("Found you in array:" + uname + "here:" + pos);
                    if(pos >= 0)
                    {   
                        System.out.println("Validation password for:" + uname);
                        if(passwords[pos].equals(pword) && !loggedOn[pos])
                        {
    }

解决方案

Your names array is not sorted:

String[] names = {"bradley","john","jim","clarke"};

which is a requirement of binarySearch() (and binary searching algorithm in general):

The range must be sorted into ascending order

Sort it first and it'll work like a charm:

String[] names = {"bradley","clarke","jim","john"};

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