需要帮助我的Java NetBeans Raffle程序

Question

I'm new to java programming and currently making this raffle program. Here is the sample output of the program.

Welcome to raffle 2013!
The Prize is <10 million - 100 million> //this is random. I already made.
Ticket number: <Generating unique 10 digits numbers>

//these are the required information for the user.
Name:
Address:
Contact:
Birthday:

//The final output

The winner of <PRIZE> is <NAME>, Ticket number.

I already have written some source code and I think I'm almost there. Unfortunately, I encountered a problem with the ticket number. The ticket number must generate 5 times with 10 digits number. The output must show the winner name together with his/her ticket number but the ticket number wasn't show and state that it is null. Here are the syntax I already made.

public class raffle2013 {

  //Title: Raffle 2013
  public static final int SIZE = 5;
  public static final int SIZE1 = 5;
  private static short x;
  private static String randomNumber;

  public static void main(String[] args) {
    String[] names;
    names = new String[SIZE];
    String[] winner;
    winner = new String[SIZE1];
    System.out.println("Welcome To Raffle 2013");

    long Low = 10000000;
    long High = 100000000;
    long randomPrize = (long) (Math.random() * High - Low) + Low;
    System.out.println("The Prize is " + " " + randomPrize);
    for (int a = 0; a < winner.length; a++) {
        long randomNumber = (long) (Math.random() * 9000000000L);
        System.out.println("Ticket number: " + randomNumber);
        Scanner scan = new Scanner(System.in);
        System.out.print("Name " + ":");
        winner[a] = scan.nextLine();
        Scanner scan2 = new Scanner(System.in);
        System.out.print("Address" + ":");
        names[x] = scan.nextLine();
        Scanner scan3 = new Scanner(System.in);
        System.out.print("Contact" + ":");
        names[x] = scan.nextLine();
        Scanner scan4 = new Scanner(System.in);
        System.out.print("Birthday" + ":");
        names[x] = scan.nextLine();
        System.out.println(" ");
    }
    Random random = new Random();
    int w = random.nextInt(SIZE1);
    System.out.println("The winner of" + " " + randomPrize + " " + "Million Peso(s)" + "is" + " " + winner[w] + "," + " " + "Ticket Number:" + " " + randomNumber);
  }
}

Note: the program can generate 10 digits unique numbers for the ticket number and generate it 5 times together with the names, however I have a problem of choosing the ticket number winner.

Here is the output in java netbeans:

run:
Welcome To Raffle 2013
The Prize is  38375493
Ticket number: 1991318978
Name :a
Address:a
Contact:a
Birthday:a

Ticket number: 194313423
Name :b
Address:b
Contact:b
Birthday:b

Ticket number: 6017170047
Name :c
Address:c
Contact:c
Birthday:c

Ticket number: 274411236
Name :d
Address:d
Contact:d
Birthday:d

Ticket number: 6183250376
Name :e
Address:e
Contact:e
Birthday:e

The winner of 38375493 Million Peso(s)is a, Ticket Number: null<--- bug
BUILD SUCCESSFUL (total time: 18 seconds)

the last output must show the winner name together with his/her ticket number. I hope you could help me. Please :)

Answer 1

Looks like you're running into an issue with scope. You may also be slightly confused about data types, but let's see...

randomNumber is assigned as a long inside of your loop, but it is declared as a static String inside your class . The declaration inside of the loop is not applicable when coming to a wider scope (that is, inside of your main method), so you won't get any pertinent values from randomNumber .

That's weird in and of itself - the different data types don't make sense to me. You also don't need the static declaration of randomNumber either - it's only ever used in main , so you could just declare it there.

To get around that, you have to wrap the output from your random input instead, and drop the declaration:

randomNumber = Long.toString(Double.valueOf(Math.random() * 9000000000L).longValue());

Also, as a code smell, you've got too many Scanner instances; you should only really need one. I leave that as an exercise to the reader to clean up and refactor.

Answer 2

Actually you have created randomNumber of String type outside the loop , while inside you have created randomNumber of type long...this long type is only accessible within the loop and the randomNumber you are calling is the one which is string type and it is null because you havent assigned any value to it..

What you have to do is to have an array of the randomNumber and save the ticket numbers as well and in the last as you are getting the winner[w] the same way you get randomNumber[w]

Answer 3

Similar to storing the winner, the ticket number has to be stored as well, and recalled when the output is printed

import java.util.Random;
import java.util.Scanner;

public class raffle2013 {

    // Title: Raffle 2013

    public static final int SIZE = 5;
    public static final int SIZE1 = 5;
    private static short x;
    private static String randomNumber;

    public static void main(String[] args) {
        String[] names;
        names = new String[SIZE];
        String[] winner;
        winner = new String[SIZE1];
        long[] ticketNumber = new long[SIZE1];
        System.out.println("Welcome To Raffle 2013");

        long Low = 10000000;
        long High = 100000000;
        long randomPrize = (long) (Math.random() * High - Low) + Low;
        System.out.println("The Prize is " + " " + randomPrize);
        for (int a = 0; a < winner.length; a++) {
            long randomNumber = (long) (Math.random() * 9000000000L);
            System.out.println("Ticket number: " + randomNumber);
            Scanner scan = new Scanner(System.in);
            System.out.print("Name " + ":");
            winner[a] = scan.nextLine();
            ticketNumber[a] = randomNumber;
            Scanner scan2 = new Scanner(System.in);
            System.out.print("Address" + ":");
            names[x] = scan.nextLine();
            Scanner scan3 = new Scanner(System.in);
            System.out.print("Contact" + ":");
            names[x] = scan.nextLine();
            Scanner scan4 = new Scanner(System.in);
            System.out.print("Birthday" + ":");
            names[x] = scan.nextLine();
            System.out.println(" ");

        }

        Random random = new Random();
        int w = random.nextInt(SIZE1);

        System.out.println("The winner of" + " " + randomPrize + " "
                + "Million Peso(s)" + "is" + " " + winner[w] + "," + " "
                + "Ticket Number:" + " " + Long.toString(ticketNumber[w]));
    }
}