用Java扫描行

Question

What's wrong with the code? It won't let me write the input for each one of them..I wanted to read how many editions, the year and city of each edition, and it jumps to the loop and won't let me put input.

public class Competition {

    private static ArrayList<Edition> editions = new ArrayList<Edition>();
    private static Scanner scan = new Scanner(System.in);

    public static void main(String[] args) {

        String newCity = null;
        int newYear = 0;
        int itineration = 0;
        int numberEditions = 0;
        Edition newEdition = new Edition(newCity, newYear);

        System.out.println("How many editions would you like to create?");
        numberEditions = scan.nextInt();

        while (itineration < numberEditions) {
            System.out.println("\nEnter the city and year of the Edition you would"
                    + " like to create: ");

            System.out.println("Year: ");
            newYear = scan.nextInt();
            System.out.println("City: ");
            newCity = scan.nextLine();

            editions.add(newEdition);
            itineration++;
        }

        for (int index = 0; index < editions.size(); index++) {
            System.out.println("Music Festival'" + editions.get(index).getYear()
                    + ", "
                    + editions.get(index).getCity());

        }
    }
}

Answer 1

You need to consume extra line after reading year. and also you need to create new Edition for each input and add it to the list in while loop:

while (itineration < numberEditions) {
    System.out.println("\nEnter the city and year of the Edition you would"
            + " like to create: ");

    System.out.println("Year: ");
    newYear = scan.nextInt();

    scan.nextLine();

    System.out.println("City: ");
    newCity = scan.nextLine();

    Edition newEdition = new Edition(newCity, newYear);
    editions.add(newEdition);
    itineration++;
}

Hope it helps

Answer 2

You need to create new instance of Edition inside the while loop.

    while (itineration < numberEditions) {
        System.out.println("\nEnter the city and year of the Edition you would"
                + " like to create: ");

        System.out.println("Year: ");
        newYear = scan.nextInt();
        System.out.println("City: ");
        newCity = scan.nextLine();

       Edition newEdition = new Edition(newCity, newYear);
        editions.add(newEdition);
        itineration++;
    }

Answer 3

There are some problems with the Scanner class if you don't know how to use it. Some people suggest using a buffered reade r. I would recommend researching both objects before using either one.

Answer 4

You have made 2 errors.

1. Make new Edition instances inside loop
2. use Scanner.next() to get the input String . Scanner.nextLine() is invalid.

Working code:

 while (itineration < numberEditions)
        {
            System.out.println("\nEnter the city and year of the Edition you would" + " like to create: ");

            System.out.println("Year: ");
            newYear = scan.nextInt();
            System.out.println("City: ");
            newCity = scan.next();

            editions.add(new Edition(newCity, newYear));
            itineration++;
        }

Answer 5

为Scanner创建新对象。现在就可以输入值了。

newCity = new Scanner(System.in).nextLine();