输出问题

Question

以下代码在运行后为我创建了一个错误，它投影了第一行“请输入矩形的长度”。正确，但是输入数字后的下一行是“输入矩形的长度：请输入矩形的宽度”。然后，在我第二次输入后，它将创建一个错误并使我的代码崩溃。澄清一下，我并不是要像那样将它们并排放置。任何帮助，将不胜感激。谢谢！

import java.util.Scanner;

public class AreaRectangle {
    public static void main(String[] args) {
        double length,     // The rectangle's length
                width,     // The rectangle's width
                area;      // The rectangle's area

        // Get the rectangle's length from the user.
        length = getLength();
        System.out.print("Enter the length of " +
                "the rectangle: ");

        // Get the rectangle's width from the user.
        width = getWidth();
        System.out.print("Enter the width of " +
                "the rectangle: ");

        // Get the rectangle's area.
        area = getArea(length, width);
        System.out.print("The area of the " +
                "rectangle is: ");

        // Display the rectangle data.
        displayData(length, width, area);
        System.out.print("Enter the length of " +
                "the rectangle: ");
    }

    public static double getLength() {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Please enter length of a rectangle.");
        double length = keyboard.nextDouble();
        System.out.println("The length of the rectangle is " + length);
        return length;
    }

    public static double getWidth() {
        Scanner keyboard = new Scanner(System.in);
        double width;
        System.out.println("Please enter width of a rectangle.");
        width = keyboard.nextDouble();
        System.out.println("The width of the rectangle is " + width);
        return width;
    }

    public static double getArea(double length, double width) {
        double area = length * width;
        System.out.println("The area of the rectangle is " + area);
        return area;
    }

    public static double displayData(double length, double width, double
            area) {
        System.out.println("The length of the rectangle is: \t" + length);
        System.out.println("The width of the rectangle is: \t" + width);
        System.out.println("The area of the rectangle is: \t" + area);
    }
}

Answer 1

您忘记了从getLength函数返回值。

只需在其上添加return语句，它将起作用。

您已声明：

public static double displayData(....)

因此您必须返回一个双精度值或将函数声明更改为

public static void displayData

您的主要功能还有另一个问题：可以删除主作用域上的所有println。您也可以在getArea函数中删除println。您的代码如下：

import java.util.Scanner;

公共类AreaRectangle {     公共静态void main（String [] args）{         double length，//矩形的长度                 width，//矩形的宽度                 区域; //矩形的区域

    // Get the rectangle's length from the user.
    length = getLength();


    // Get the rectangle's width from the user.
    width = getWidth();

    // Get the rectangle's area.
    area = getArea(length, width);

    // Display the rectangle data.
    displayData(length, width, area);

}

public static double getLength() {
    Scanner keyboard = new Scanner(System.in);
    System.out.println("Please enter length of a rectangle.");
    double length = keyboard.nextDouble();
    System.out.println("The length of the rectangle is " + length);
    return length;
}

public static double getWidth() {
    Scanner keyboard = new Scanner(System.in);
    double width;
    System.out.println("Please enter width of a rectangle.");
    width = keyboard.nextDouble();
    System.out.println("The width of the rectangle is " + width);
    return width;
}

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

public static void displayData(double length, double width, double
        area) {
    System.out.println("The length of the rectangle is: \t" + length);
    System.out.println("The width of the rectangle is: \t" + width);
    System.out.println("The area of the rectangle is: \t" + area);
}

}

，控制台输出就可以满足您的需求。

Answer 2

1. 从main()中删除所有提示。
   其他方法中也包含正确的提示。
2. 在打开Scanner对象的每种方法中，
   不要忘记在return语句keyboard.close();之前关闭它。

Answer 3

这是您的代码。看看它是如何实现的，然后尝试添加一些新功能，例如矩形的参数或对角线。并不难。

public class Main {
    private static double lengthOfRectangle;
    private static double widthOfRectangle;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Input the length of the rectangle: \n");
        lengthOfRectangle = scanner.nextDouble();
        System.out.println("Input the length of the rectangle: \n");
        widthOfRectangle = scanner.nextDouble();
        System.out.printf("Length: %s - Width: %s - Area of your rectangle is %s", lengthOfRectangle,widthOfRectangle,lengthOfRectangle*widthOfRectangle);

    }




}