Question

I have the following piece of code. I do not understand why its not working.

I’d really appreciate help on this.

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

class ReadFiles {
    String [] codes = new String[99];
    int i = 0;

    private Scanner readCodes;

    public void openCodesFile() {
        try {
            readCodes = new Scanner(new File("C:/Users/Carlo/Desktop/Files/codes.txt"));
        } catch (Exception e) {
            System.out.println("Could not locate the data file!");
        }
    }

    public void readCodesFile() {

        while(readCodes.hasNext()) {
            codes[i] = readCodes.nextLine();
            i++;
            System.out.println(codes[i]);
        }
    }

    public void closeCodesFile() {
        readCodes.close();
    }
}

class NewHardware {
    public static void main(String[] args) {
        ReadFiles codesRead = new ReadFiles();
        codesRead.openCodesFile();
        codesRead.readCodesFile();
        codesRead.closeCodesFile();
    }
}

The output prints out “null” a bunch of times.

Also, I want to be able to not only print out the codes but use the codes array in the class NewHardware and manipulate it (print it out, truncate it, etc).

I was thinking of doing the following with readCodesFile():

public String readCodesFile() {

        while(readCodes.hasNext()) {
            codes[i] = readCodes.nextLine();
            i++;
            System.out.println(codes[i]);
        }
                    return (codes[i]);
    }

Or something but it hasn’t worked just yet. Am I on the right track?

Oh, just wanted to add that the text contains the following:

G22
K13
S21
I30
H15
N23
L33
E19
U49

EDIT:

Thanks to Tony and Churk below to help me with my idiocy. I am accepting Tony’s answer basically because he challenged me to think but Churk’s answer is just as valuable.

For the second part of my question (where I asked about being able to use it in class NewHardware), I did the following:

class NewHardware {
    public static void main(String[] args) {
        ReadFiles codesRead = new ReadFiles();

        codesRead.openCodesFile();

        codesRead.readCodesFile();

        for (int i = 0; i < 9; i++) {
            System.out.println("\n\n" + codesRead.codes[i]);
        }

        codesRead.closeCodesFile();
    }
}

This is of course not the final program code but this has helped me get the basic idea. Hope this helps others too.

Answer 1

Look carefully at your readCodesFile() method. Look at every line. What is it doing? Can you explain it to us?