java - 为什么我无法打印值(value)？

Question

我编写了以下程序:

import java.util.Scanner ;

public class Triangle
{
   public static void main ( String [] args )
   {
       Scanner scan = new Scanner ( System.in ) ; // new object named "scan"

       // Next lines scan ribs values into a,b,c parameters
       System.out.println ( "Please enter first rib value : "  ) ;
       int a = scan.nextInt () ; 
       System.out.println ( "Please enter second rib value : "  ) ;
       int b = scan.nextInt () ; 
       System.out.println ( "Please enter third rib value : "  ) ;
       int c = scan.nextInt () ; 
       if ( ! ( ( a >= 1 ) && ( b>=1 ) && ( c>=1 ) ) ) 
            System.out.println ( "One or more of the ribs value is negative !!\nPlease enter a positive value ONLY ! "  ) ;     
       else if ( ! ( (a <= b+c) && ( b <= a+c ) && ( c <= a+b ) ) )
            System.out.println ( "Error !\n\nOne rib can not be bigger than the two others !  "  ) ;     
       else
        {
           float s = (a+b+c) / 2 ;
           double area = Math.sqrt( s * ( s-a ) * ( s-b ) * ( s-c ) ) ;
           float perimeter = s*2 ;
           System.out.println ( "Perimeter of the triangle is: "+perimeter+"\n\nArea of the triangle is: "+area) ;     
        }// end of else
        }//end of method main
  } //end of class Triangle

问题是，对于三角形肋的每个合法值，我在屏幕上得到的区域值都是 0.0。

这是为什么呢？我所做的一切似乎都很好..不是吗？!

谢谢

Answer 1

您的s变量默认在整数空间中计算，您需要使其中一个操作数浮点以避免舍入错误，例如:

float s = (a+b+c) / (float) 2;

<小时/>

您还可以考虑构建更容易阅读的 if 子句，例如，

   if ( ! ( ( a >= 1 ) && ( b>=1 ) && ( c>=1 ) ) ) 

进入

   if ( a <= 0 || b <= 0 || c <= 0 ) 

如果您想创建 Equilateral三角形第二个 if 子句可以转换自:

   else if ( ! ( (a <= b+c) && ( b <= a+c ) && ( c <= a+b ) ) )

进入

   else if (a != b || b != c)