I need help getting started

[Android]

so here is my assignment, but the instructor never went over this material in class and I'm having trouble grasping the material.

Design and implement an algorithm that deals with abstract data types (ADT) in JAVA. Create Sphere ADT. Write the following software modules or functions:
-Define the class Sphere
-Define two constructors, default and copy
-Construct a few Spheres using default and copy constructors
-Read Spheres from the standard Input device using the Scanner utility.
-Design, run, and test a driver routine (main method in a separate file)that will check the execution of the ADT and its components.

I'd just like some help getting started maybe, or a better explaination of default and copy constructors and how to use them. Thanks in advance for your help.

[JavaBean]

I guess with "copy constructor, your instructor means a constructor which takes an instance of that class and copy its properties into the new object it creates.

Try to write your own class and then we can check it.. That way you will learn better i guess.

[maxisms]

i guess it means overloading constructors