Thread: Beginner program w/ file, arrays and binary search algorithm - HELP!

Hi there. I am a beginner and I can't seem to figure out what is wrong with my code.
I am trying to write a program that will ask a user to enter a number between 1 and 10,000 and then report whether the number is prime. But when I test it, it keeps telling me that every single number is composite, even though it actually is prime. It is for an assignment for school so I am not allowed to use any more advanced java than what I have here.

The program is supposed to:
Read the numbers from a file
Store them in an array
Implement a the binary search method to search for the number entered by the user.

import java.util.Scanner;
import java.io.*;
 
public class Primes {
   public static void main(String[] args) throws IOException {
       File inFile = new File("primes.txt");
       Scanner input = new Scanner(inFile);
       Scanner keyboard = new Scanner(System.in);
       String primes[] = new String [1229];
       String numSearch;
       int i = 0;
 
       while(input.hasNext()) {
           primes[i] = input.next();
           i++;
       }
 
       System.out.println("Welcome!\n");
 
       System.out.print("Enter a number from 1 to 10,000 or 'x' to exit: ");
       numSearch = keyboard.next();
       while(!numSearch.equals("x")) {
           int location = binarySearch(primes, numSearch);
           if (location == -1) {
               System.out.println(numSearch + " is composite.\n");
           }
           else {
               System.out.println(numSearch + " is prime!\n");
           }
           System.out.print("Enter a number from 1 to 10,000 or 'x' to exit: ");
           numSearch = keyboard.next();
       }
 
       System.out.println("Goodbye!");
 
       input.close();
       keyboard.close();
   }
 
   private static int binarySearch(String[] arr, String key) {
   int low = 0;
   int high = arr.length;
 
   while (low <= high) {
       int mid = (low + high) / 2;
       if (arr[mid].equals(key)) {
           return mid;
       }
       else if (key.compareTo(arr[mid]) < 0) {
           high = mid - 1;
       }
       else {
           low = mid + 1;
       }
   }
 
   return -1;
 
}
 
 
}