Write an interface class Calculator.

The class has the following properties:
Methods add, subtract, multiply, and divide. 
All methods are of void type and each takes a single integer as a parameter.
A method getResult, which has no parameters. 
This method returns a double-type floating-point number.




import java.util.Random;

public class Test{
    public static void main(String[] args){
        final Random r = new Random();
        
        System.out.println("Testing the calculator interface...");
        
        Calculator c = new CalculatorTest();
        
        c.add(1);
        System.out.println("add(int number) ok");
        
        c.subtract(1);
        System.out.println("subtract(int number) ok");

        c.multiply(1);
        System.out.println("multiply(int number) ok");
        
        c.divide(1);
        System.out.println("divide(int number) ok");
        
        double d = c.getResult();
        System.out.println("getResult() ok");

    }
}




//ADD
interface Calculator {
    void add(int number);
    void subtract(int number);
    void multiply(int number);
    void divide(int number);
    double getResult();
}




Testing the calculator interface...
add(int number) ok
subtract(int number) ok
multiply(int number) ok
divide(int number) ok
getResult() ok