java - 代码运行但没有给我正确的输出

Question

我对编码还很陌生。我不确定如何跨方法移动输入值。我尝试了不同的方法，但它总是给我一个错误。我也很好奇您将如何返回多个值。就像让我们说，而不是有 getLength() 和 getWidth() 会有一个叫做 getInput() 的长度和宽度都将被返回。

    import java.util.Scanner;  // Needed for the Scanner class
/**
   This program calculates the area of a rectangle.
*/
public class Rectangle
{
   //main method
   public static void main(String[] args)
   {  
      float length = 0;
      float width = 0;
      float area = 0;


      getLength();
      getWidth();   
      calcArea(length, width);
      displayData(area);
   }

   //method 2
   public static float getLength()
   { 
      // Create a Scanner object to read from the keyboard.
      Scanner keyboard = new Scanner(System.in);

      System.out.print("Enter Length: ");
      float length = keyboard.nextFloat();

      return length;     

   }

   public static float getWidth()
   {
      // Create a Scanner object to read from the keyboard.
      Scanner keyboard = new Scanner(System.in);

      System.out.print("Enter Width: ");
      float width = keyboard.nextFloat(); 

      return width;

   }


   public static float calcArea(float length, float width)
   {
     float area = length*width;

     System.out.print("\nxxxx "+area);

     return area;

   }

   public static void displayData(float area)
   {
      System.out.print("\nThe area of the rectangle is "+area);
   }

}

Answer 1

您的问题来自于非 void 方法将返回值这一事实。如果您不将这些值分配给任何变量，Java 将不会对它们执行任何操作。

float length = 0;
float width = 0;
float area = 0;

// Values are retrieved, but must be assigned to variables
length = getLength();
width = getWidth();   
area = calcArea(length, width);

我强烈建议您尝试一些更直观的方法。我知道您是编码新手，但请尝试解决这个问题，看看它能给您带来什么。 OOP 是 Java 的核心组件，通常最好尽可能使用它。

矩形.java:

public class Rectangle
{

    private float length;
    private float width;

    public Rectangle(float length, float width)
    {
        this.length = length;
        this.width = width;
    }

    public float getArea()
    {
        return length * width;
    }

    public float getLength()
    {
        return length;
    }

    public float getWidth()
    {
        return width;
    }
}

主类:

public static void main(String[] args)
{
    // Only open one stream at a time
    // Opening multiple without closing the previous may cause some problems in the future
    Scanner keyboard = new Scanner(System.in);

    System.out.print("Enter Length: ");
    float length = keyboard.nextFloat();
    System.out.print("Enter Width: ");
    float width = keyboard.nextFloat();

    // Remember to close the stream when you are finished using it
    keyboard.close();

    // Create a new rectangle with the length and width that was given by the user
    Rectangle rect = new Rectangle(length, width);
    // Round the area to the nearest tenth of a decimal place and display results
    System.out.printf("The area of the rectangle is %.1f", rect.getArea());
}