Question

Java Please - Design and implement a class Triangle. A constructor should accept the lengths of a triangle’s 3 sides (as integers) and verify that the sum of any 2 sides is greater than the 3rd(i.e., that the 3 sides satisfy the triangle inequality). The constructor should mark the triangle as valid or invalid; do not throw an exception. Provide get and set methods for the 3 sides, and recheck for validity in the set methods. Provide a toString method to display the triangle and whether it is a valid triangle. Provide 4 other boolean-returning methods: isRight, isIsosceles (only 2 sides are equal), isEquilateral, and isInvalid. Provide a driver in a separate source file to test your class.

Please make sure to use integers, not doubles.

All instance variables must be private

Must include a toString method as stated

The main routine must be in a separate from the .java file(s) for the class(es) that are being defined - otherwise they are not reusable.

Then

Modify the Triangle class to throw an exception in the constructor and set routines if the triangle is not valid (i.e., does not satisfy the triangle inequality). Modify the main routine to prompt the user for the sides of the triangle and to catch the exception and re-prompt the user for valid triangle sides. In addition, for any valid triangle supply a method to compute and display the area of the triangle using Herod’s method: where a, b, and c are the lengths of the sides and p is 1/2 of the perimeter of the triangle, A = [p(p-a)(p-b)(p-c)]^1/2. The area, A, should be a double displayed with 2 digits after the decimal point. Supply a getPerimeter method to compute the perimeter as an integer. Display the triangle, its area and perimeter. Allow the user to repeatedly enter triangle sides and do not exit the process until the user enters 0 for a side length. Here is a sample dialog:

Enter the sides of the triangle as integers

Enter 0 to quit:

Enter side 1: 3

Enter side 2: 4

Enter side 3: 5

Triangle with sides: 3 4 5

Is right

Is not isosceles

Is not equilateral

Area = 6.00

Perimeter = 12

Enter the sides of the triangle as integers

Enter 0 to quit:

Enter side 1: 1

Enter side 2: 1

Enter side 3: 2

Not a valid triangle

Enter the sides of the triangle as integers

Enter 0 to quit:

Enter side 1: -1

Enter side 2: 2

Enter side 3: 3

Not a valid triangle

Enter the sides of the triangle as integers

Enter 0 to quit:

Enter side 1: 1

Enter side 2: 2

Enter side 3: 2

Is not right

Is isosceles

Is not equilateral

Area = 0.97

Perimeter = 5

Enter the sides of the triangle as integers

Enter 0 to quit:

Enter side 1: 0

Exiting

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Please and thank you!!

Answer 1

Please find the answer below, all the details are mentioned in the comments:

Triangle.java

public class Triangle {
    //fields to store the values
    private int sideA;
    private int sideB;
    private int sideC;
    private boolean isValid;

    //constructor
    public Triangle(int sideA, int sideB, int sideC) throws Exception {
        this.sideA = sideA;
        this.sideB = sideB;
        this.sideC = sideC;

        if (checkValid()) {
            isValid = true;
        } else {
            isValid = false;
        }
    }


    // Function to calculate for validity
    public boolean checkValid() throws Exception {
        // check condition
        if (sideA + sideB <= sideC || sideA + sideC <= sideB || sideB + sideC <= sideA)
            throw  new Exception("Not a valid triangle");
        else
            return true;
    }

    //getter and setters
    public int getSideA() {
        return sideA;
    }

    public void setSideA(int sideA) throws Exception {
        this.sideA = sideA;
        if (checkValid()) {
            isValid = true;
        } else {
            isValid = false;
        }
    }

    public int getSideB() {
        return sideB;
    }

    public void setSideB(int sideB) throws Exception {
        this.sideB = sideB;
        if (checkValid()) {
            isValid = true;
        } else {
            isValid = false;
        }
    }

    public int getSideC() {
        return sideC;
    }

    public void setSideC(int sideC) throws Exception {
        this.sideC = sideC;
        if (checkValid()) {
            isValid = true;
        } else {
            isValid = false;
        }
    }

    //check of the triangle is right
    public boolean isRight() {
        if (sideA * sideA + sideB * sideB == sideC * sideC
                || sideB * sideB + sideC * sideC == sideA * sideA
                || sideA * sideA + sideC * sideC == sideB * sideB) {
            return true;
        }
        return false;
    }

    //check if the triangle is isosceles is not
    public boolean isIsosceles() {
        if (sideA == sideB || sideB == sideC || sideC == sideA) {
            return true;
        }
        return false;
    }

    //check if the triangle is equilateral or not
    public boolean isEquilateral() {
        if (sideA == sideB && sideB == sideC) {
            return true;
        }
        return false;
    }

    //check if the triangle is valid or not
    public boolean isInvalid() throws Exception {
        return checkValid();
    }

    //to print the details of the triangle
    @Override
    public String toString() {
        return "Triangle with sides:" + sideA + " " + sideB + " " + sideC;
    }

    //get the area of the triangle
    public double area() {
        int perimeter = perimeter() / 2;
        double area = (perimeter) * (perimeter - sideA) * (perimeter - sideB) * (perimeter - sideC);
        area = Math.sqrt(area);
        return area;
    }

    //get the perimeter of the triangle
    public int perimeter(){
        return sideA + sideB + sideC;
    }
}

TriangleTest.java

import java.util.Scanner;

public class TriangleTest {
    //main method to test the triangle class
    public static void main(String[] args) {
        //to check if continue or not
        boolean continueLoop = true;
        Scanner sc = new Scanner(System.in);
        int a, b, c;
        while (continueLoop) {
            //get the values from the user
            System.out.println("Enter the sides of the triangle as integers");
            System.out.println("Enter 0 to quit:");

            System.out.print("Enter side 1: ");
            a = sc.nextInt();
            if (a == 0) {
                continueLoop = false;
                break;
            }

            System.out.print("Enter side 2: ");
            b = sc.nextInt();

            System.out.print("Enter side 3: ");
            c = sc.nextInt();

            //check all the details
            try {
                Triangle triangle = new Triangle(a, b, c);
                System.out.println(triangle.toString());
                if (triangle.isRight())
                    System.out.println("Is right");
                else
                    System.out.println("Is not right");

                if (triangle.isIsosceles())
                    System.out.println("Is Isosceles");
                else
                    System.out.println("Is not isosceles");

                if (triangle.isEquilateral())
                    System.out.println("Is equilateral");
                else
                    System.out.println("Is not equilateral");

                System.out.printf("Area = %.2f\n",triangle.area());
                System.out.println("Perimeter = " + triangle.perimeter());
            } catch (Exception ex) {
                System.out.println(ex.getMessage());
            }

        }
    }
}

Output:

Please let us know in the comments if you face any problems.