Create four new classes for each
real-world object. For each new class that you have created, create an
interface that defines its behavior, then require your class to implement it.
Omit one or two methods and try compiling. What does the error look like?
Create a small program that
defines some fields. Try creating some illegal field names and see what kind of
error the compiler produces.
In the program you created, try
leaving the fields uninitialized and print out their values. Try the same with
a local variable and see what kind of compiler errors you can produce.