Question

Consider the following class: import java.util.Scanner; public class MyPoint { private double x; private double y; public MyPoint() { this(0, 0); } public MyPoint(double x, double y) { this.x = x; this.y = y; } // Returns the distance between this MyPoint and other public double distance(MyPoint other) { return Math.sqrt(Math.pow(other.x - x, 2) + Math.pow(other.y - y, 2)); } // Determines if this MyPoint is equivalent to another MyPoint public boolean equals(MyPoint other) { return this.x == other.x && this.y == other.y; } // Returns a String like “(4.5, -4.8)” public String toString() { return "(" + x + ", " + y + ")"; } // Creates and returns a new MyPoint based on data from a // Scanner. If there’s nothing to be read in, it returns null. public static MyPoint read(Scanner sc) { if (!sc.hasNext()) return null; double x = sc.nextDouble(); double y = sc.nextDouble(); return new MyPoint(x, y); } } Your job is to write a class called Triangle. Here’s the UML diagram: Triangle - a: MyPoint - b: MyPoint - c: MyPoint + Triangle(a: MyPoint, b: MyPoint, c: MyPoint) + equals(other: Triangle): boolean + toString(): String + perimeterLength(): double + read(sc: Scanner): Triangle Notes: The data fields represent the three corners of a triangle. The equals method should determine if this Triangle equals other. Hint: use the equals method of MyPoint. The toString method should return a String like “a = (5.5, 4.0), b = (34.6, -3.3), c = (0, 6)”. The perimeterLength method should return the length of the perimeter. Hint: use the distance method of MyPoint. The read method should be defined as usual; it should be similar to the read method in part 3 of Codelab Project 2. That is, if there’s nothing more to read in, return null. Otherwise, read in the appropriate number of MyPoints (hint: use the read method of MyPoint) and return a new Triangle.

Answer 1

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code...

MyPoint.java

import java.util.Scanner;

public class MyPoint {

    private double x;

    private double y;

    public MyPoint() {

        this(0, 0);

    }

    public MyPoint(double x, double y) {

        this.x = x;

        this.y = y;

    }

    // Returns the distance between this MyPoint and other

    public double distance(MyPoint other) {

        return Math.sqrt(Math.pow(other.x - x, 2) + Math.pow(other.y - y, 2));

    }

    // Determines if this MyPoint is equivalent to another MyPoint

    public boolean equals(MyPoint other) {

        return this.x == other.x && this.y == other.y;

    }

    // Returns a String like "(4.5, -4.8)"

    @Override

    public String toString() {

        return "(" + x + ", " + y + ")";

    }

    // Creates and returns a new MyPoint based on data from a // Scanner. If there’s

    // nothing to be read in, it returns null.

    public static MyPoint read(Scanner sc) {

        if (!sc.hasNext())

            return null;

        double x = sc.nextDouble();

        double y = sc.nextDouble();

        return new MyPoint(x, y);

    }

}

Triangle.java

import java.util.Scanner;

// class Triangle

public class Triangle {

    // private MyPoints a,b,c

    private MyPoint a;

    private MyPoint b;

    private MyPoint c;

    // constructor

    public Triangle(MyPoint a, MyPoint b, MyPoint c) {

        this.a = a;

        this.b = b;

        this.c = c;

    }

    // toString method

    @Override

    public String toString() {

        return "a = "+a+", b = "+b+", c = "+c;

    }

    // equals method return true if all the points of both the triangle are same

    public boolean equals(Triangle other) {

        if (other != null) {

            return this.a.equals(other.a) && this.b.equals(other.b) && this.c.equals(other.c);

        }

        return false;

    }

    // return perimeter using distance method of MyPoing class

    public double perimeterLength() {

        double perimeter = a.distance(b) + b.distance(c) + a.distance(c);

        return perimeter;

    }

    // return a new Triangle instance by reading the points from read method of MyPoint class

    public static Triangle read() {

        Scanner sc = new Scanner(System.in); // creating Scanner instance

        // reading three points

        MyPoint a = MyPoint.read(sc);

        MyPoint b = MyPoint.read(sc);

        MyPoint c = MyPoint.read(sc);

        // returning new triangle instance

        return new Triangle(a, b, c);

    }

    // main method

    public static void main(String[] args) {

        // creating a Triangle instance using Trangle.read() method

        Triangle triangle1 = Triangle.read();

        // calling PerimeterLenght() to get perimeter

        System.out.format("Perimeter : %.2f\n", triangle1.perimeterLength());

        // printing the triangle

        System.out.println(triangle1);

        // creating a triangle my passing MyPoint instance

        Triangle triangle2 = new Triangle(new MyPoint(5.5, 4.0), new MyPoint(34.6, -3.3), new MyPoint(0, 6));

        // printing triangle2

        System.out.println(triangle2);

        // calling equals method to check both are equals

        System.out.println(triangle1.equals(triangle2));

    }   

}

outputs..