Java Interface

An interface in Java is essentially abstract class- all members are abstract. Java doesn't allow you to extend multiple classes. But Java does allow you to implement multiple interfaces. Actually interfaces are about polymorphism, whereas, inheriting methods are about code reuse. Interface can be extended.
 (1st page)
package iacday6;

public class IACDay6 {

    public static void main(String[] args) {
       
       
        Calculator c = new Calculator();
       
        System.out.println("Sum "+c.sum(10, 15));
        System.out.println("Sub " + c.subtract(10, 5));
        System.out.println("Mul " + c.mul(10, 5));
        System.out.println("Div "+ c.div(10, 5));
       
    }

}

--------------------------------------------------------------------------------------------------------

(2nd page)

package iacday6;
public interface Calculation {
   
    double sum(double  x, double y);
    double subtract(double  x, double y);
    double mul(double  x, double y);
    double div(double  x, double y);
}

class Calculator implements Calculation{

    @Override
    public double sum(double x, double y) {
        return x + y;
    }

    @Override
    public double subtract(double x, double y) {
        return x - y;
    }

    @Override
    public double mul(double x, double y) {
        return x * y;
    }

    @Override
    public double div(double x, double y) {
        return x /y;
    }

}
 -------------------------------------------------------------------------------------------Output----------
Sum 25.0
Sub 5.0
Mul 50.0
Div 2.0
BUILD SUCCESSFUL (total time: 0 seconds)