Question

I had a quick questions about prompting and accepting a file name, then making the file-text a scanner object.

I want the program to prompt the user to enter the name of a file, until he gets one which exists, then for the file-text to be used as a scanner object.

This is the code I have so far, it works to the point where I exit the while {} loop, but then when I try and process the scanner item like while (input.hasNextLine()) { it gives me an error saying it can’t find the scanner item.

It’s probably a silly mistake, but I just cannot seem to get it.

The whole code is below:

import java.io.*;
import java.util.*;

public class PersonalityTest {

public static void main(String[] args) throws FileNotFoundException {

    boolean isFile = false;

        Scanner sc = new Scanner(System.in);
        System.out.print("Input file name? ");
        String fileName = sc.next();
        File inputFile = new File(fileName);

    while (isFile == false) {    
        if (inputFile.exists()) {
            Scanner input = new Scanner(inputFile);
            isFile = true;
        }            
    }

    while(input.hasNextLine()) {

    }
}

Answer 1

You can’t access input outside the if statement, sice the compiler is not sure, it will pass the test, you can do this:

Scanner sc = new Scanner(System.in);
Scanner input = null;
boolean isFile = false;

while (isFile == false){    

    System.out.print("Input file name? ");
    String fileName = sc.next();
    File inputFile = new File(fileName);

    if (inputFile.exists()){
        input = new Scanner(inputFile);
        isFile = true;
    }            
}

But will throw a NullPointerException if it is null.

I changed the code a little bit, that way, it will not exceed if the file doesn’t exist.