Task 10 Computers

June 8, 2024 Deadline: Jun 24 (inclusive)

Create three classes:

1. CalculatingDevice

• Constructor: Takes a name (String).
• Method:

  public String calculate(double x, double y)

  This method calculates the sum of its arguments and returns a string (not a number) with the name of the machine and the result of the addition.
• Static Method:

  public static void printRes(CalculatingDevice[] a, double x, double y)

  This method takes an array of calculating machines and arguments x and y. It prints the results of calculations with these arguments for each machine from the array.

2. Calculator

• Extends CalculatingDevice.
• Override Method:

  public String calculate(double x, double y)

  This method gets the result of addition by invoking super.calculate and adds the result of subtraction (as a string).

3. Computer

• Extends Calculator.
• Override Method:

  public String calculate(double x, double y)

  This method gets the result of addition and subtraction by invoking super.calculate and adds, as a string, the results of multiplication and division.

The following program:

public class Computers {
    public static void main(String[] args) {
        CalculatingDevice[] arr = {
            new Computer("Cray"),
            new CalculatingDevice("Abacus"),
            new Calculator("HP")
        };
        CalculatingDevice.printRes(arr, 21, 7);
    }
}

Should print something like:

Cray: 21.0+7.0=28.0; 21.0-7.0=14.0; 21.0*7.0=147.0; 21.0/7.0=3.0
Abacus: 21.0+7.0=28.0
HP: 21.0+7.0=28.0; 21.0-7.0=14.0

Implementation

CalculatingDevice.java

public class CalculatingDevice {
    private String name;

    public CalculatingDevice(String name) {
        this.name = name;
    }

    public String calculate(double x, double y) {
        double sum = x + y;
        return name + ": " + x + "+" + y + "=" + sum;
    }

    public static void printRes(CalculatingDevice[] a, double x, double y) {
        for (CalculatingDevice device : a) {
            System.out.println(device.calculate(x, y));
        }
    }
}

Calculator.java

public class Calculator extends CalculatingDevice {

    public Calculator(String name) {
        super(name);
    }

    @Override
    public String calculate(double x, double y) {
        String result = super.calculate(x, y);
        double difference = x - y;
        return result + "; " + x + "-" + y + "=" + difference;
    }
}

Computer.java

public class Computer extends Calculator {

    public Computer(String name) {
        super(name);
    }

    @Override
    public String calculate(double x, double y) {
        String result = super.calculate(x, y);
        double product = x * y;
        double quotient = x / y;
        return result + "; " + x + "*" + y + "=" + product + "; " + x + "/" + y + "=" + quotient;
    }
}

Computers.java

public class Computers {
    public static void main(String[] args) {
        CalculatingDevice[] arr = {
            new Computer("Cray"),
            new CalculatingDevice("Abacus"),
            new Calculator("HP")
        };
        CalculatingDevice.printRes(arr, 21, 7);
    }
}

Explanation:

1. CalculatingDevice Class:

   • Has a constructor to initialize the name.
   • The calculate method sums the two numbers and returns a formatted string with the result.
   • The printRes static method iterates over an array of CalculatingDevice objects and prints their calculations.

2. Calculator Class:

   • Extends CalculatingDevice.
   • Overrides the calculate method to include subtraction in the result string.

3. Computer Class:

   • Extends Calculator.
   • Overrides the calculate method to include multiplication and division in the result string.

4. Computers Class:

   • Contains the main method.
   • Creates an array of CalculatingDevice objects including instances of Computer, CalculatingDevice, and Calculator.
   • Calls the printRes method to print the results for each device with the provided arguments.

Output:

When you run the Computers class, it should produce the following output:

Cray: 21.0+7.0=28.0; 21.0-7.0=14.0; 21.0*7.0=147.0; 21.0/7.0=3.0
Abacus: 21.0+7.0=28.0
HP: 21.0+7.0=28.0; 21.0-7.0=14.0

One File

Computers.java

public class Computers {

    public static void main(String[] args) {
        CalculatingDevice[] arr = {
            new Computer("Cray"),
            new CalculatingDevice("Abacus"),
            new Calculator("HP")
        };
        CalculatingDevice.printRes(arr, 21, 7);
    }
}

// Base class
class CalculatingDevice {
    private String name;

    public CalculatingDevice(String name) {
        this.name = name;
    }

    public String calculate(double x, double y) {
        double sum = x + y;
        return name + ": " + x + "+" + y + "=" + sum;
    }

    public static void printRes(CalculatingDevice[] a, double x, double y) {
        for (CalculatingDevice device : a) {
            System.out.println(device.calculate(x, y));
        }
    }
}

// Subclass extending CalculatingDevice
class Calculator extends CalculatingDevice {

    public Calculator(String name) {
        super(name);
    }

    @Override
    public String calculate(double x, double y) {
        String result = super.calculate(x, y);
        double difference = x - y;
        return result + "; " + x + "-" + y + "=" + difference;
    }
}

// Subclass extending Calculator
class Computer extends Calculator {

    public Computer(String name) {
        super(name);
    }

    @Override
    public String calculate(double x, double y) {
        String result = super.calculate(x, y);
        double product = x * y;
        double quotient = x / y;
        return result + "; " + x + "*" + y + "=" + product + "; " + x + "/" + y + "=" + quotient;
    }
}