java - Java 中的三角形分析

Question

我想提示用户输入三角形的 3 条边。然后判断三角形是直角三角形、等边三角形还是等腰三角形。但我的程序只是在错误处理中捕获错误，并在尝试获取 side(1) 时退出程序。所以我的问题是你知道是什么原因造成的或者我的代码有什么问题吗？

驱动程序TestTriangle.java

public class TestTriangle { 
  public static void main(String[] args) {
    System.out.println("Welcome to the Triangle Program");
    System.out.println();

    Triangle myTriangle = new Triangle();
    myTriangle.buildTriangle();

    System.out.println();
    System.out.println("My analysis of this triangle is");
    System.out.println();

    myTriangle.classifyTriangle();

    String prettyPerim = String.format("%.3g", myTriangle.perimeter());
    String prettyArea = String.format("%.3g", myTriangle.area());

    System.out.println("\tThe area of the triangle is " + prettyArea + ".");
    System.out.println("\tThe perimeter of the triangle is " + prettyPerim + ".");
   }
}

程序Triangle.java

import java.util.Scanner;
import java.util.InputMismatchException;

public class Triangle {
  public static final double TOLERANCE = 0.0001;

  private double min;
  private double mid;
  private double max;  
  private Scanner input;

  public Triangle() {
    double side1 = 0.0, side2 = 0.0, side3 = 0.0;
  }

  public void buildTriangle() {
    double side1 = getSide(1);
    double side2 = getSide(2);
    double side3 = getSide(3);

    // if side1 is greater than side2, the min is side1 and the max is side2
    if (side1 < side2) {
      min = side1;
      max = side2;
    // otherwise the min is side2 and the max is side1
    } else {
      min = side2;
      max = side1;
    }

    // if side3 is less than the min value, then the mid value is the min value and the min value is side3
    if (side3 < min) {
      mid = min;
      min = side3;
    // if side3 is greater than the max value then the mid is the max and the max is side3
    } else if (side3 > max) {
      mid = max;
      max = side3;
    // otherwise the mid is side3
    } else {
      mid = side3;
    }
  }

  public double getSide(int index) {
    System.out.print("Please enter the length of side " + index + ": ");
    double sideVal = 0.0;
    try{
      sideVal = input.nextDouble();
    } catch (Exception e) {
      System.out.println("You did not enter a valid input. Exiting.");
      System.exit(1);
    }
    return sideVal;
  }

  public void classifyTriangle() {
    // if the max value is greater than the min and the mid combined it is not a triangle, exit the program.
    if (max > min + mid) {
      System.out.println("Not a triangle");
      System.exit(1);
    }
    else if (((Math.pow(min, 2)) + (Math.pow(mid, 2))) == (Math.pow(max, 2))) {      
      System.out.println("This is a right triangle");
    }
    else if (max == min || min == mid || max == mid) {
      if (max == min && min == mid && max == mid) {      
        System.out.println("This is an equilateral triangle");
      }
      else {
        System.out.println("This is an isosceles triangle");
      }
    }
  }

  public double perimeter() {
    // calculate the perimeter
    double perimeter = max + mid + min;
    return perimeter;
  }

  public double area() {
    // calculate the area
    double semi = (max + mid + min) / 2;
    double product = (semi - max) * (semi - mid) * (semi - min) * semi;
    double area = Math.sqrt(product);
    return area;
  }
}

Answer 1

您需要初始化您的输入

    input = new Scanner(System.in);