如何在Java中找到数组中字符串的索引号

Question

I have no idea if I'm coding this efficiently, or even correctly, but I want to input a name, address, and phone number. I then want to have input find a match from the input array, and use that same index number to print the corresponding information.

import java.util.*;

public class NameAddress {

    public static void main(String[] args) {

        Scanner ui = new Scanner(System.in);
        System.out.println("Welcome to the name collecting database");
        String []names = new String[5];
        String []address = new String[5];
        String []phone = new String [5];
        int count =0;

        while (count<=5)
        {
            System.out.println("Please enter the name you would like to input");
            names[count] =ui.next();
            System.out.println("Name has been registered into Slot "+(count+1)+" :"+Arrays.toString(names));
            System.out.println("Please enter the address corresponding with this name");
            ui.nextLine();
            address[count] = ui.nextLine();
            System.out.println(names[count]+" has inputted the address: "+address[count]+"\nPlease input your phone number");
            phone[count]=ui.nextLine();
            System.out.println(names[count]+"'s phone number is: "+phone[count]+"\nWould you like to add a new user? (Yes or No)");

            if (ui.next().equals("No"))
            {
                System.out.println("Please enter a name to see matched information");
                String name = ui.next();
                if(name.equals(names[count]))
                {
                    System.out.println("Name: "+names[count]+"\nAddress: "+address[count]+"\nPhone: "+phone[count]);
                }
                count=6;
            }
            count++;
        } 
    }

}

Answer 1

        System.out.println("Please enter a name to see matched information");
        String name = ui.next();
        for(int i = 0; i <names.length;i++){
        if(name.equals(names[i]))
        {
            System.out.println("Name: "+names[i]+"\nAddress: "+address[i]+"\nPhone: "+phone[i]);
        }
        }

Answer 2

if(name.equals(names[count])) will work only if the name user is searching is at the current index of names . So you have to check every item in the array to determine whether it exists in the array. You can do this:

int itemIndex = Arrays.asList(names).indexOf(name);
if(itemIndex>=0) // instead of if(name.equals(names[count]))
{
    // rest of the codes; use the itemIndex to retrieve other information
}
else
{
    System.out.println(name + " was not found");
}

Or manually loop over the names array as others showed.

Answer 3

It seems like you have data input already done.

As for data retrieval by searching, if you don't care about efficiency, then you could iterate over the entire array to see if the text inputted matches any element in your array using

int searchIndex = 0;
for (int i = 0; i < names.length; i++) {
    if (searchString.equals(names[i])) {
        searchIndex = i;
    }
}

where searchString would be the string input by the user to find the element in the array. The code block above assumes you don't have duplicate data, but you could easily tweak the returned index to contain an array of indexes that contain your data, if you wish. You'd then have an index number (or index numbers) with which you could use to find the rest of the data in your other arrays.