@Override public void add(int number) {this.result += number;}

Week 6: Methods of OO Programming/06. The Calculator implements an interface

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+Now write a class 'Calculator' that implements the interface 'CalculatorInterface' written in the previous task.
+
+The class should have a CONSTRUCTOR that initializes the calculator to its initial state (result is 0.0).
+
+Additionally, the class has the methods add, subtract, multiply, and divide, 
+coming from the interface, which all change the result in memory as their names suggest.
+
+The method getResult() returns the result in memory.
+
+
+
+
+Example of using the class:
+Calculator calc = new Calculator();
+System.out.println(calc.getResult());
+
+calc.add(10);
+System.out.println(calc.getResult());
+
+calc.subtract(5);
+System.out.println(calc.getResult());
+
+calc.multiply(3);
+System.out.println(calc.getResult());
+
+calc.divide(2);
+System.out.println(calc.getResult());
+ 
+
+The program prints:
+0.0
+10.0
+5.0
+15.0
+7.5
+
+
+
+
+
+import java.util.Random;
+
+public class Test {
+    public static void main(String[] args) {
+        final Random r = new Random();
+        
+        
+        System.out.println("Testing the class Calculator...");
+        
+        CalculatorInterface calc = new Calculator();
+        
+        System.out.println("The class implements the interface CalculatorInterface!");
+        
+        System.out.println("Testing addition...");
+        int[] numbers = {2, 4, 3, 7};
+        for (int number : numbers) {
+            calc.add(number);
+            System.out.println("Added " + number + ", now the result is " + calc.getResult());
+        }
+        
+        System.out.println("Testing subtraction...");
+        numbers = new int[]{2, 1, 3, 2};
+        for (int number : numbers) {
+            calc.subtract(number);
+            System.out.println("Subtracted " + number + ", now the result is " + calc.getResult());
+        }
+        
+        System.out.println("Testing multiplication...");
+        numbers = new int[]{2, 1, 3};
+        for (int number : numbers) {
+            calc.multiply(number);
+            System.out.println("Multiplied by " + number + ", now the result is " + calc.getResult());
+        }
+        
+        System.out.println("Testing division...");
+        numbers = new int[]{2, 2, 5};
+        for (int number : numbers) {
+            calc.divide(number);
+            System.out.println("Divided by " + number + ", now the result is " + calc.getResult());
+        }
+    }
+}
+
+
+//ADD
+class Calculator implements CalculatorInterface {
+    private double result;
+    
+    public Calculator() {
+        this.result = 0.0;
+    }
+
+    @Override
+    public void add(int number) {
+        this.result += number;
+    }
+
+    @Override
+    public void subtract(int number) {
+        this.result -= number;
+    }
+
+    @Override
+    public void multiply(int number) {
+        this.result *= number;
+    }
+
+    @Override
+    public void divide(int number) {
+        this.result /= number;
+    }
+
+    @Override
+    public double getResult() {
+        return this.result;
+    }
+}
+
+
+
+
+Testing the class Calculator...
+The class implements the interface CalculatorInterface!
+Testing addition...
+Added 2, now the result is 2.0
+Added 4, now the result is 6.0
+Added 3, now the result is 9.0
+Added 7, now the result is 16.0
+
+Testing subtraction...
+Subtracted 2, now the result is 14.0
+Subtracted 1, now the result is 13.0
+Subtracted 3, now the result is 10.0
+Subtracted 2, now the result is 8.0
+
+Testing multiplication...
+Multiplied by 2, now the result is 16.0
+Multiplied by 1, now the result is 16.0
+Multiplied by 3, now the result is 48.0
+
+Testing division...
+Divided by 2, now the result is 24.0
+Divided by 2, now the result is 12.0
+Divided by 5, now the result is 2.4
+
+
+
+
+
+