Java SE做while循环问题

Question

我的Java应用程序在编译代码时遇到问题，它说它找不到符号 roomLength
。应用程序应该执行的操作是提示用户输入房间名称，然后如果该房间名称为“退出”，则必须关闭该程序。否则会提示输入房间的长度，宽度和高度。如果这些尺寸中的任何一个等于或小于零，它将再次提示输入尺寸。

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;
}
}

这是我的主要方法。

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();
    if(roomName.equals("quit"))
    {
        userInput.close();
    } else
    {
        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();

        Room r = new Room(roomName, roomLength, roomWidth, roomHeight);
        }
        while (roomLength > 0 || roomWidth > 0 || roomHeight > 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());

    }
}
}

提前致谢！;）

还有一个几乎与此问题类似的问题，只是它应该循环回到第一个提示，允许用户输入另一个房间的名称和尺寸。

干杯!

Answer 1

您正在尝试访问在声明范围之外的变量。您必须在声明外部声明变量，do以便可以在中访问它们while：

    double roomLength;
    double roomWidth;
    double roomHeight;
    do
    {
    Scanner dimensionsInput = new Scanner(System.in);
    System.out.print("Please enter the dimensions of the room, length, width and height accordingly");

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

    Room r = new Room(roomName, roomLength, roomWidth, roomHeight);
    }
    while (roomLength > 0 || roomWidth > 0 || roomHeight > 0);

但是我现在看到这Room也是用错误的范围声明的。如果要随后访问它，则必须在循环之前声明它。因此，一个更简单的解决方案可能是：

    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);

顺便说一句，直到所有尺寸都为0，才循环播放似乎不对== 0。我怀疑您要检查。