Question

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])
                        {
    }

Answer 1

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"};