Assignment 3: Java Object-Oriented Program
Due: Thursday, 7 May 2009 at 11:59pm
Overview
The purpose of this assignment is for you to gain experience with object-oriented programming in Java,
and in particular the ideas of inheritance, dynamic binding (virtual methods), overriding and overloading
methods. It will also give you some exposure to how some programming language features are implemented,
i.e., what happens “behind the scenes” when you execute a program. Although no language provides the
exact features in this assignment, several languages (e.g., Awk, Icon, Lisp, CLUS, SISAL) do provide similar
features. Your program needs to implement several abstractions. The first abstraction is an Element, of
which there are many kinds: MyInteger,MyChar and Sequence.MyInteger and MyChar respectively
are class-based abstractions of int and char. Class Sequence is a dynamic array of Element objects.
ASequence object, thus stores objects of type MyInteger,MyChar and Sequence. The following is an
example of a Sequence object:
[ 1 ‘a’ [1 3 ‘b’]]
In this example, the Sequence object contains three Element objects: 1,‘a’ and another Sequence
object [1 3 ‘b’]. Thus, a Sequence object may contain nested Sequence objects.
Part 1: Class Definitions
The first part of this homework requires you to define and implement the classes and their member methods.
Use the names Element,MyInteger,MyChar and Sequence for your class definitions. Note that there is
an is-a relationship between Element and MyInteger,MyChar and Sequence classes.
•Define constructor for each class. MyInteger objects are initialized to 0,MyChar objects to ’0’, and
Sequence to an empty sequence, i.e., a sequence with zero elements.
•Define Get and Set methods for Char and Integer:
class MyChar extends Element {
public MyChar() { ... }
public char Get() { ... }
public void Set(char val) { ... }
...
}
class MyInteger extends Element {
public MyInteger() { ... }
public int Get() { ... }
public void Set(int val) { ... }
...
}
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