Problem with the first project in the Android Techdegree

package com.hariidaran;

import com.hariidaran.model.Imxporter;
import com.hariidaran.model.Jar;
import com.hariidaran.model.Prompter;

public class Game {

    public static void main(String[] args) {
        Jar jar = new Jar();
        Prompter prompter = new Prompter(jar);
        Imxporter imxporter = new Imxporter(prompter);

        imxporter.importFrom("scores.txt");
        prompter.play();
        imxporter.exportTo("scores.txt");
    }
}

package com.hariidaran.model;

import java.util.Random;

public class Jar {
    private String mItemName;
    private Random mGenerator;
    private int mItems;
    private int mMaxItems;

    public Jar() {
        mGenerator = new Random();
    }

    // -HELPER-METHODS--------------------------------------------

    public String getItemName() {
        return mItemName;
    }

    public void setItemName(String itemName) {
        mItemName = itemName;
    }

    public int getItems() {
        return mItems;
    }

    public int getMaxItems() {
        return mMaxItems;
    }

    public void setMaxItems(int maxItems) {
        mMaxItems = maxItems;
    }

    // -MAIN-METHODS----------------------------------------------

    public void fill() {
        mItems = mGenerator.nextInt(mMaxItems) + 1;
    }

    public boolean isEmpty() {
        return mItems == 0;
    }
}

package com.hariidaran.model;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Prompter {
    private Jar mJar;

    private BufferedReader mReader;

    private String mName;
    private int mNumberOfGuesses = 0;
    private String mFinalStatement;

    public Prompter(Jar jar) {
        mJar = jar;
        mReader = new BufferedReader(new InputStreamReader(System.in));
    }

    // -HELPER-METHODS--------------------------------------------

    // Checks if a string is a number
    private static boolean isNaN(String string) {
        try {
            float number = Float.parseFloat(string);
        } catch (NumberFormatException nfe) {
            return true;
        }

        return false;
    }

    // Prints out the string (title) in a specific way
    private void printTitle(String title) {
        System.out.printf("%n%s%n", title.toUpperCase());
        System.out.printf("========================%n%n");
    }

    // Explains the game
    private void explainGame() {
        System.out.printf("%n" +
                "This is a game where you have to guess the" +
                "%n" +
                "number of items in a jar (which you can't see)." +
                "%n%n" +
                "As you are the admin of this game, you can" +
                "%n" +
                "enter what the items in the jar are to be" +
                "%n" +
                "called. You can also enter the maximum number" +
                "%n" +
                "of items." +
                "%n%n");
    }

    // Prompt for guess
    private void promptForGuess() throws IOException {
        System.out.printf("%nYour goal is to guess how many %ss are there in there " +
                        "(and it can hold from 1 to %d %ss).",
                mJar.getItemName(), mJar.getMaxItems(), mJar.getItemName());

        // Asks you to start the game
        System.out.printf("%n%nReady? (press ENTER or RETURN to play)");
        mReader.readLine();

        // Start guessing
        String guess = "";

        List<String> guesses = new ArrayList<>();

        // While your guess isn't the answer, guess again
        while (!guess.equals(mJar.getItems() + "")) {
            System.out.printf("%nGuess: ");
            guess = mReader.readLine();

            // Send out warning if 1 or 0, special characters and letters are entered
            if (isNaN(guess) || (Integer.parseInt(guess) == 0 && Integer.parseInt(guess) == 1)) {
                System.out.println("No special characters or letters or 0 allowed. Try again.");
            } else if (guesses.contains(guess)) {
                System.out.println("Number already guessed before.");
            } else {
                // The guess counter gets incremHented
                guesses.add(guess);
                mNumberOfGuesses++;
            }
        }
    }

    private void showStatement() {
        // Expectation to match
        boolean isMatchedExpectation = mNumberOfGuesses < Math.round(mJar.getMaxItems() / 2);

        // If the player matches the expectation
        if (isMatchedExpectation) {
            // If the player took 1 try to guess the answer
            if (mNumberOfGuesses == 1) {
                mFinalStatement = String.format("%nYou took 1 try to guess that there is ");
            }
            // If the player took more than 1 try to guess the answer
            else {
                mFinalStatement = String.format("%nYou took %d tries to guess that there are ", mNumberOfGuesses);
            }

            // If there is only one
            if (mJar.getItems() == 1) {
                mFinalStatement += "1 " + mJar.getItemName() + " in the jar,";
            } else {
                mFinalStatement += mJar.getItems() + " " + mJar.getItemName() + "s in the jar,";
            }

            mFinalStatement += " and it's like you knew the answer! Good job!";

            System.out.print(mFinalStatement);
        } else {
            System.out.printf("%nYou took %d tries to guess that there are %d %ss in the jar," +
                            " but you could've done better. Try again.",
                    mNumberOfGuesses, mJar.getItems(), mJar.getItemName());
        }
    }

    public ArrayList<String> getResults() {
        String name = mName;
        String itemsPresent = mJar.getItems() + " " + mJar.getItemName();
        String maxItems = mJar.getMaxItems() + " " + mJar.getItemName();
        String numberOfGuesses = mNumberOfGuesses + "";

        String[] results = {name, itemsPresent, maxItems, numberOfGuesses};

        return new ArrayList<>(Arrays.asList(results));
    }

    // Prints out an error
    public void printError(Exception e) {
        System.out.printf("%n%nOops! Something went wrong in the program.%n" +
                          "Try running the program again.%n%n");
        e.printStackTrace();
    }

    // -MAIN-METHODS----------------------------------------------

    // Play the program
    public void play() {

        explainGame();

        try {
            startAdminSetup();
            startGame();
        } catch (IOException ioe) {
            printError(ioe);
        }
    }

    // Administrator Setup
    private void startAdminSetup() throws IOException {
        // Prints out "ADMINISTRATIVE SETUP"
        printTitle("Administrator Setup");

        // Asks for the player's name
        System.out.print("Name of the player:  ");
        mName = mReader.readLine();

        // Asks the player what to call the items
        System.out.print("Name of item (it should be singular):  ");
        String itemName = mReader.readLine();
        if (!(itemName.equals("") || itemName.equals(String.format("%n"))) || isNaN(itemName)) {
            mJar.setItemName(itemName);
        } else {
            mJar.setItemName("item");
        }

        String maxItemsString = "";
        int maxItems = 0;

        // Expectation to match
        boolean isNotMatched = isNaN(maxItemsString) ||
                maxItems == 0 ||
                maxItems == 1 ||
                maxItemsString.equals(String.format("%n")) ||
                maxItemsString.equals("f");

        // Loops till maxItemsString is a number
        while (isNotMatched) {
            System.out.printf("Maximum number of %ss in the jar:  ", mJar.getItemName());
            maxItemsString = mReader.readLine().trim().toLowerCase();

            // Send out warning if 1 or 0, special characters and letters are entered
            try {
                maxItems = Integer.parseInt(maxItemsString);
            } catch (NumberFormatException nfe) {
                System.out.println("1 or 0, and special characters, letters are not allowed.");
            }

            isNotMatched = isNaN(maxItemsString) ||
                    maxItems == 0 ||
                    maxItems == 1 ||
                    maxItemsString.equals(String.format("%n")) ||
                    maxItemsString.equals("") ||
                    maxItemsString.equals("f");
        }

        // The maximum number of items it can hold is assigned
        mJar.setMaxItems(maxItems);
    }

    // Start the game
    private void startGame() throws IOException {
        mJar.fill();

        // Prompt for guess
        promptForGuess();

        // Shows the score
        showStatement();
    }
}

package com.hariidaran.model;

import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Imxporter {
    private Prompter mPrompter;
    private List<List<String>> mScores;

    public Imxporter(Prompter prompter) {
        mPrompter = prompter;
    }

    public void importFrom(String fileName) {
        try (
                FileInputStream fis = new FileInputStream(fileName);
                BufferedReader reader = new BufferedReader(new InputStreamReader(fis));
        ) {
            String line;

            while ((line = reader.readLine()) != null) {
                String[] args = line.split("\\|");
                List<String> score = new ArrayList<>(Arrays.asList(new String[] {
                        args[0], args[1], args[2], args[3]
                }));

                mScores.add(score);

                System.out.printf("%s found out there were %s in a jar " +
                                "which could hold %s, in %s tries.%n",
                        args[0], args[1], args[2], args[3]);
            }
        } catch (IOException ioe) {
            mPrompter.printError(ioe);
        }
    }

    public void exportTo(String fileName) {
        try (
                FileOutputStream fos = new FileOutputStream(fileName);
                PrintWriter writer = new PrintWriter(fos);
        ) {
            List<String> score = mPrompter.getResults();

            mScores.add(score);

            for (List<String> args : mScores) {
                writer.printf("%s|%s|%s|%s",
                args.get(0), args.get(1), args.get(2), args.get(3));
            }

            System.out.printf("%n%nSaving scores...");
        } catch (IOException ioe) {
            mPrompter.printError(ioe);
        }
    }
}