Universidad Carlos III de Madrid

Program a constructor for the Point class. It must receive both point coordinates as input parameters.

The String toString() method has a special meaning for objects in Java. This method is used to get a text representation of the object as a string.

Program the String toString() method of the Point class so that it returns a string with the representation of the point like in the following example: "(23, -3)". The first number represents the x coordinate of the point, and the second one the y coordinate.

Now you have to create a class to test the previous code. Program a class called TestPoint which has a main method. This method must receive, as command line arguments, the x and y coordinates, then create a new Point object with those coordinates and print a text representation of the object to the standard output.

The program must check that the number of command line arguments received is correct.

Take into account that the parseDouble method of the Double class transforms a string of characters to a double primitive type.

It is common that object's attributes are declared as private to avoid uncontrolled accesses from other parts of the program. To provide such access from outside code, there are special methods. Those methods usually begin with the following strings: "get" (read access) and "set" (write access).

Program the following access methods that return the coordintate values x and y in the Point class:

public double getX() {
    /* ... */
}

public double getY() {
    /* ... */
}

Modify the code of your TestPoint class to check that its behaviour is correct.

Program the following method of the Point class, which returns the distance from the point to the origin of the coordinates:

public double distance() {
  /* ... */
}

Overload the previous method with the following one, which receives another object of the Point class and returns the distance between the point to which the method belongs and the point received as parameter:

public double distance(Point anotherPoint) {
    /* ... */
}

Modify the code of your TestPoint class to check that its behaviour is correct.

Program a method of the Point class that returns the quadrant in which the point is located as an int value:

The prototype of the method is shown below:

public int quadrant()  {
  /* ... */
}

Modify the code of your TestPoint class to check that its behaviour is correct.

Program a method of the Point class that receives, as input parameter, an array of Point objects and returns a reference to the object of the array that represents the nearest point to the current object (this). The prototype of the method is as follows:

public Point nearest(Point[] otherPoints) {
  /* ... */
}

Modify the code of your TestPoint class to check that its behaviour is correct.

A triangle is fully defined by three of its vertices. These vertexes can be represented as objects of the Point class.

Program the Triangle class with its attributes and a constrctor that receives three points (vertices) as input parameters.

Program the sideLengths() method of the Triangle class. It must return an array of three decimals (double) that represents, respectively, the length of each side of the triangle. The prototype of the method is as follows:

public double[] sideLengths() {
    /* ... */
}

Program a class to test the Triangle class.

Program the basic structure of the class: its attributes and two constructors. The first constructor has two integers as its arguments (numerator and denominator). The second constructor will receive only one argument, an integer, an will create the rational representation of that ordinary integer, this is, having 1 as the denominator. This second constructor must be implemented using the first one.

Add a String toString() method to the class. It must return a textual representation of rational numbers as shown in this examples: "-5 / 2", "1 / 3", "6", "-7". Notice that only the numerator is shown when the denominator is 1.

Modify the first constructor to create uniform objects according to this set of rules:

We recommend using a private method to implement this operations, which should be invoqued by the constructor.

You should be able to calculate the maximum common divisor of two integers by using the following code:

    private int gcd() {
        int a = /* put here the attribute that represents the numerator */
        int b = /* put here the attribute that represents the denominator */
        while (b != 0) {
            int tmp = b;
            b = a % b;
            a = tmp;
        }
        if (a < 0) {
            a = -a;
        }
        return a;
    }

Add another method that receives an object of the class Rational and returns a new object of that same class representing the sum of the current object (this) and the object passed as an argument.

    public Rational sum(Rational other) {
        (...)
    }

Repeat the previous section, but returning the product of the objects.

    public Rational multiply(Rational other) {
        (...)
    }

Overload the methods from the two previous sections to receive the numerator and denominator of the operand instead of its Rational representation. You must reuse your previous code by calling the original sum and multiply methods from the overloaded ones.

    public Rational sum(int otherNumerator, int otherDenominator) {
        (...)
    }

    public Rational multiply(int otherNumerator, int otherDenominator) {
        (...)
    }