Let’s learn java program to find area of circle and rectangle using interface.

## Java program to find area of circle and rectangle using interface

We can use interface to calculate area of circle and rectangle.

Here’s java program.

interface FindArea { doublepi= 3.14159265359; double calculate(double a, double b); } class Rectangle implements FindArea { public double calculate(double a, double b) { return(a * b); } } class Circle implements FindArea { public double calculate(double a, double b) { return(pi * a * a); } } public class FindAreaUsingInterface { public static void main(String[] args) { Rectangle rect = new Rectangle(); Circle cir = new Circle(); FindArea area; area = rect; System.out.println("Area of rectangle is: " + area.calculate(50, 30)); area = cir; System.out.println("Area of circle is: " + area.calculate(10, 10)); } }

**Output:**

Area of rectangle is: 1500.0

Area of circle is: 314.15926535899996

Also read – variables in java