Java do while loop back to the beginning of application

问题

This question is a follow-up from this link Java SE do while loop issues

This is an application asking for a room's name then second prompt to ask for its dimensions to perform some calculations. right after everything has been done, the application should be able to return back to the first prompt asking for the name of room etc.

class Room
{
private String name;
private double length;
private double width;
private double height;

public Room(String r, double l, double w, double h)
{
    name = r;
    length = l;
    width = w;
    height = h;
}


public String getName()
{
    return name;
}

public double getLength()
{
    return length;
}

public double getWidth()
{
    return width;
}

public double getHeight()
{
    return height;
}

public double getArea()
{
    double area = length*width;
    return area;
}

public double getVolume()
{
    double volume = length*width*height;
    return volume;  
}

public void setName(String s)
{
    name = s;
}
}

And my main method running the application.

import java.util.Scanner;

class TestRoom
{
public static void main(String [] args)
{
    Scanner userInput = new Scanner(System.in);
    System.out.println("Please enter the name of room");

    String roomName = userInput.next();
    while(!(roomName.equals("quit")))
    {           
        Room r;
        do
        {
            Scanner dimensionsInput = new Scanner(System.in);
            System.out.print("Please enter the dimensions of the room, length, width and height accordingly");

            double roomLength = dimensionsInput.nextDouble();
            double roomWidth = dimensionsInput.nextDouble();
            double roomHeight = dimensionsInput.nextDouble();

            r = new Room(roomName, roomLength, roomWidth, roomHeight);
        }
        while (r.getLength() == 0 || r.getWidth() == 0 || r.getHeight() == 0);


        System.out.println("The name of room: " + r.getName() + " Dimensions: L= " + r.getLength() + 
                                " X " + "W= " + r.getWidth() + " X " + "H= " + r.getHeight());
        System.out.println("Area of room= " + r.getArea());
        System.out.println("Volume of room= " + r.getVolume());

    }
    userInput.close();
}
}

Right now the application only returns to the second prompt instead of the first one so could you guys help me on this? Thanks in advance again guys!

回答1:

You don't need to declare two scanners. You obviously had to include the first prompt into the outer while loop as well.

"Fixed" code:

import java.util.Scanner;

class TestRoom
{
    public static void main(String[] args)
    {
        Scanner userInput = new Scanner(System.in);
        String roomName = "";

        while (!(roomName.equals("quit")))
        {
            System.out.println("Please enter the name of room");

            roomName = userInput.next();

            Room r;

            do
            {
                System.out
                        .print("Please enter the dimensions of the room, length, width and height accordingly");

                double roomLength = userInput.nextDouble();
                double roomWidth = userInput.nextDouble();
                double roomHeight = userInput.nextDouble();

                r = new Room(roomName, roomLength, roomWidth, roomHeight);
            } while (r.getLength() == 0 || r.getWidth() == 0
                    || r.getHeight() == 0);

            System.out.println("The name of room: " + r.getName()
                    + " Dimensions: L= " + r.getLength() + " X " + "W= "
                    + r.getWidth() + " X " + "H= " + r.getHeight());
            System.out.println("Area of room= " + r.getArea());
            System.out.println("Volume of room= " + r.getVolume());
        }

        userInput.close();
    }
}

回答2:

Try this:

 class TestRoom {

    static Scanner userInput = new Scanner(System.in);

    static Scanner dimensionsInput = new Scanner(System.in);

    public static void main(String[] args) {

        while(true) {
            prompt();
        }

    }

    private static void prompt() {
        System.out.println("Please enter the name of room");

        String roomName = userInput.next();

        if (roomName.equals("quit")){
            userInput.close();
            dimensionsInput.close();
            System.exit(0);
        }
        Room r;
        do
        {
            System.out
                    .print("Please enter the dimensions of the room, length, width and height accordingly");

            double roomLength = dimensionsInput.nextDouble();
            double roomWidth = dimensionsInput.nextDouble();
            double roomHeight = dimensionsInput.nextDouble();
            r = new Room(roomName, roomLength, roomWidth, roomHeight);
        } while (r.getLength() == 0 || r.getWidth() == 0
                || r.getHeight() == 0);


        System.out.println("The name of room: " + r.getName()
                + " Dimensions: L= " + r.getLength() + " X " + "W= "
                + r.getWidth() + " X " + "H= " + r.getHeight());
        System.out.println("Area of room= " + r.getArea());
        System.out.println("Volume of room= " + r.getVolume());
    }
}

来源：https://stackoverflow.com/questions/24475590/java-do-while-loop-back-to-the-beginning-of-application