java - 非法三角形异常

Question

我的作业有一些问题，希望你们能帮助我。作业是这样的:

(IllegalTriangleException) Programming Exercise 11.1 defined the Triangle class with three sides. In a Triangle, the sum of any two sides is greater than the other side. The Triangle class must adhere to this rule. Create the IllegalTriangleException class, and modify the constructor of the Triangle class to throw an IllegalTriangleException object if a triangle is created with sides that violate the rule, as follows:

   /** Construct a triangle with the specified sides */
    public Triangle(double side1, double side2, double side3)
       throws IllegalTriangleException {
        //Implement it
    }

好的。这是三角形类。

import java.lang.Math;

public class Triangle extends GeometricObject {
 private double side1 = 1.0;
 private double side2 = 1.0;
 private double side3 = 1.0;

 public Triangle() {

}

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

 public double getSide1() {
    return side1;
}

 public double getSide2() {
    return side2;
}

 public double getSide3() {
    return side3;
}

 public void setSide1(double side1) {
    this.side1 = side1;
}

 public void setSide2(double side2) {
    this.side2 = side2;
}

 public void setSide3(double side3) {
    this.side3 = side3;
}

 public double getArea() {
     double p = getPerimeter() / 2;
     return Math.sqrt(p * ((p - side1) * (p - side2) * (p - side3)));
}

 public double getPerimeter() {
     return side1 + side2 + side3 ;
}

 public String toString() {
     return " Triangle: Side 1 = " + side1 + " Side 2 = " + side2
             + " Side 3 = " + side3;
}

}

IllegalTriangleException 类:

 public class IllegalTriangleException extends Exception {
private double perimeter;

 /** Construct an exception*/
  public IllegalTriangleException(double perimeter) {
    super( "The sum of any two sides is greater than the other side" +  perimeter);
    this.perimeter = perimeter;
}
 /**return the side*/
  public double getPerimeter() {
    return perimeter;
}
}

这是TriangleWithException类:

  public class TriangleWithException {
    //The perimeter of the triangle
    private double perimeter;
    private double side1 = 1.0;
    private double side2 = 1.0;
    private double side3 = -1.0;

    //Number of objects created
    private static int numberOfObjects = 0;

        //construct a triangle with perimeter 
    public TriangleWithException(double side1, double side2, double side3)  {

    }
    //Construct a triangle with a specified perimeter.
    public TriangleWithException(double newPerimeter) {
        setPerimeter(newPerimeter);
        numberOfObjects++;

    }
    //Return perimeter
    public double getPerimeter() {
        return perimeter;
    }

    //set new perimeter
    public void setPerimeter(double newPerimeter) throws IllegalArgumentException {
        if (newPerimeter >= 0)
            perimeter = newPerimeter;
        else
            throw new IllegalArgumentException("Any two sides needs to be grater than the other side");

    }
    // Return numberOFObjects
    public static int getNumberOfObjects() {
        return numberOfObjects;
    }

    //return area of triangle
    public double findArea() {
        double p = getPerimeter() / 2;
        return Math.sqrt(p * ((p - side1) * (p - side2) * (p - side3)));
    }
    }

最后是测试程序。

public class TestTriangleWithException {
public static void main(String[] args) {
    try {
      new TestTriangleWithException(/** What goes here?*/);
      new TestTriangleWithException(/** What goes here?*/);
      new TestTriangleWithException(/** What goes here?*/);
}
    catch (IllegalTriangleException ex) {
        System.out.println(ex);
}
    System.out.println("Number of objects created: " + 
            TriangleWithException.getNumberOfObjects());
}
}
  class TriangleWithException {
//Perimeter
private double perimeter;

//number of objects created
private static int numberOfObjects = 0;

//Construct a triangle with a specified perimeter
public TriangleWithException() throws IllegalTriangleException {
    double side1; 
    double side2; 
    double side3;
}

//construcj a triangle 
public TriangleWithException(double newPerimeter)
throws IllegalTriangleException {
    if (newPerimeter >= 0)
        perimeter = newPerimeter;
        else
            throw new IllegalTriangleException(newPerimeter);

}

//Return numberofobjects
public static int getNumberOfObjects() {
    return numberOfObjects;

}

//Return the area of the triangle 
/** How do define getPerimeter for the type IllegalTriangleException?
 * How do i resolve side1, side2 and side3 as variables?*/
public double findArea() {
     double p = getPerimeter() / 2;
    return Math.sqrt(p * ((p - side1) * (p - side2) * (p - side3)));
}
}

所以，我目前面临的问题是这些:

我需要修改 Triangle 类的构造函数，以便在违反规则时抛出 IllegalTriangleException。

我需要弄清楚Perimeter是否是我需要的变量，而不是异常类中的边。

我是一名初学者，因此虽然这些解决方案对您来说似乎是显而易见的，但它们并不适合我。

如有任何帮助，我们将不胜感激。

Answer 1

我想应该可以帮助你。我向构造函数添加了选择语句，并帮助您处理Exception 类。如果您的 GeometricObject 类很好，那么此代码应该适合您。

import java.util.Scanner;

public class TriangleWithException {

public static void main(String[] args) throws IllegalTriangleException {

    Scanner input = new Scanner(System.in);

    // create triangle
    Triangle triangle = new Triangle();
    boolean done = false;
    double side1 = 1.0;
    double side2 = 1.0;
    double side3 = 1.0;

    System.out.println("Enter three sides: ");

    while (!done) {
        try {
            side1 = input.nextDouble();
            side2 = input.nextDouble();
            side3 = input.nextDouble();
            triangle = new Triangle(side1, side2, side3);
            done = true;
        }
        catch (IllegalTriangleException ex) {
            System.out.println(ex.getMessage());
            System.out.print("Enter three sides:  ");
            input.nextLine();
        }
    }




    System.out.println("Enter a color:  ");
    String color = input.next();
    triangle.setColor(color);

    System.out.println("Enter true or false for triangle filled: ");
    boolean filled = input.nextBoolean();
    triangle.setFilled(filled);

    System.out.println();

    System.out.println(triangle.toString() + 
            "\narea: " + triangle.getArea() + 
            "\nperimeter " + triangle.getPerimeter() +
            "\ncolor: " + triangle.getColor() + 
            "\nfilled: " + triangle.isFilled());
}

}

原始三角形类

class Triangle extends GeometricObject {

protected double side1 = 1.0;
protected double side2 = 1.0;
protected double side3 = 1.0;

public Triangle() {
}

public Triangle(double side1, double side2, double side3) throws   IllegalTriangleException {
    if (side1 >= side2 + side3)
        throw new IllegalTriangleException(side1);
    else if (side2 >= side1 + side3)
        throw new IllegalTriangleException(side2);
    else if (side3 >= side2 + side1)
        throw new IllegalTriangleException(side3);
    else {
        this.side1 = side1;
        this.side2 = side2;
        this.side3 = side3;
    }

}

public double getSide1() {
    return side1;
}

public double getSide2() {
    return side2;
}

public double getSide3() {
    return side3;
}


public double getPerimeter() {
    return side1 + side2 + side3;
}

public double getArea() {
    double p = (side1 + side2 + side3) / 2;
    double area = Math.sqrt(p * (p - side1) * (p - side2) * (p - side3));
    return area;
}

@Override
public String toString() {
    return "Triangle side 1 = " + side1 + ", side 2 = " + side2 + ", side 3 = " + side3;
}
}

IllegaTriangleException 类

class IllegalTriangleException extends Exception {

private double side = 1.0;

public IllegalTriangleException(double side) {
    super(side + " is larger than other two combined");

} 

public double getSide1() {
    return side;
}

}