1. Define an interface, called volu meArea, within which there're: - a static and final variable PI (with the value 3.14159), and two abstract methods volume(double radius) and area(double radius) Write another class MyCircle which implements the interface VolumeArea. Overriding the two methods: volume(double radius) to return a value zero (as the volume of a circle is 0), and area(double radius) to return the area of the circle. - Write the third class Mysphere, also implements VolumeArea. Overriding the two methods: volume(double radius) to calculate and return the volume of the sphere (using (4T*r*rr)/3); area(double radius) to calculate and return the surface area of the sphere (using 4 *t*t) Draw a UMI. diagram that involves volumeArea, MyCircle, and MySphere. Write a main class with the main method to test the methods in MyCircle and MySphere, set the radius of the circle and sphere both to 3.5. And display the results 2. Define an abstract class named Employee. Define following classes to inherit the abstract class n Ross class indicate the boss who get paid with a fixed salary without