The program 
Problem.java  doesn't compile. What do you need to do to make it compile?
  Why?
Use the Java API documentation for the
Box class (in the javax.swing package) 
 to help you answer the following questions.
What static nested class does Box define?
What inner class does Box define?
What is the superclass of Box's inner class?
Which of Box's nested classes can you use
    from any class?
How do you create an instance of Box's Filler
    class?
Get the file 
Class1.java. Compile and run Class1. What is the
    output?