Vfrdtyky

I have this program here that reads a list of numbers from an input file, then asks the user to enter a number. The program then looks into the file and if the number that the user entered is in the file, it will display "This number is in the file" if the number is not in the file, the program will display, "Number is not in file." The program then has to keep asking the user to enter numbers and based on the number entered, the program needs to write back the appropriate response. The first time the user is asked to enter a number, the program works correctly and prints back the correct response, the problem is that after the program asks again to enter a number, it will print back the same response as the first number entered no matter what number is entered whether it's in the file or not. Are my while loops in the wrong place? Not sure how to fix this.

package classwork7_2;

import java.util.*;

import java.io.*;



public class ClassWork7_2 {



public static void main(String args)throws IOException {



    Scanner s = new Scanner(System.in);



    int numbers = fileToArray();

    Arrays.sort(numbers);



    System.out.print("Enter a number in the file: ");

    int numb = s.nextInt();



    int i = Arrays.binarySearch(numbers, numb);



    if(i < 0){

        while(i < 0){

        System.out.print("Number is not in filen");

        System.out.print("Enter number in the file: ");

        s.nextInt();

        }

    }



     else if(i >= 0){

         while(i >= 0){

        System.out.print("This number is in the filen");

        System.out.print("Enter number in the file: ");

        s.nextInt();

         }

    }

}



public static int fileToArray() throws IOException{



    Scanner s = new Scanner(System.in);

    int array = new int[7];



    System.out.print("Enter name of file: ");

    String filename = s.nextLine();



    File f = new File(filename);

    Scanner inputFile = new Scanner(f);

    int i = 0;



    while(inputFile.hasNext()){



       array[i] = inputFile.nextInt();

       i++;

    }

        inputFile.close();

        return array;

}

}

Try this

public static void main(String args)throws IOException {



    Scanner s = new Scanner(System.in);



    int numbers = fileToArray();

    Arrays.sort(numbers);

    while(true) {

        System.out.print("Enter a number in the file: ");

        int numb = s.nextInt();



        int i = Arrays.binarySearch(numbers, numb);



        if (i < 0) {

            System.out.print("Number is not in filen");

        } else if (i >= 0) {

            System.out.print("This number is in the filen");



        }

    }

}

The problem is that you don't peform search after second input, so old result is printed out. You must re-assign user input and perform search for every input:

for(;;) {                                       // infinite loop

  System.out.println("Number is not in file");

  num = s.nextInt();                            // re-read user input

  int i = Arrays.binarySearch(numbers, numb);   // search again based on input

  if (i < 0) {

    System.out.println("Number is not in filen");

  } else {

    System.out.print("This number is in the filen");

  }

}

Just remove the first input and do everything in the loop. The main will become:

public static void main(String args) throws IOException {

    Scanner s = new Scanner(System.in);

    int numbers = fileToArray();

    Arrays.sort(numbers);



    while (true) {

        System.out.print("Enter a number in the file: ");

        int numb = s.nextInt();

        int i = Arrays.binarySearch(numbers, numb);

        if (i < 0) {

            System.out.print("Number is not in filen");

        } else {

            System.out.print("Number is in filen");

        }

    }

}

The problem is you don't have exit condition - it will ask forever. You might think for something ;)