SimpleList Class Diagram

Ancestor class specifications:

java.lang.Object
java.util.Iterator
java.util.Collection
java.util.AbstractCollection

SimpleList Class Specification

Invariant

A SimpleList object...

- is a container of zero or more objects arranged in a linear order.

- maintains an iterator that is positioned either in front of the first item, beyond the last item, or between two consecutive list items. (The iterator can be thought of as an integer that counts the number of items preceding its position.)

- maintains an isRemovable Boolean value to tell when a call to remove is allowed

Constructor Method

public SimpleList<ItemType> ( )

post: this is empty (i.e. size() == 0)

and iterator position == 0 (i.e. the iterator has zero items before it)

and isRemovable == false

Update Methods

public boolean add ( ItemType z)

post: this == this@pre with z inserted at the iterator@pre position

and size() = size()@pre + 1

and iterator == iterator@pre + 1

and isRemovable == false

note: The add method returns a boolean value to be consistent with inheritance constrains. However, in practice we shall treat this as a void method.

public void remove ()

pre: isRemovable

post: this == this@pre with the item preceding iterator@pre removed

and size() == size()@pre - 1

and iterator == iterator@pre - 1

and isRemovable == false

public void reset ()

post: iterator == 0 (i.e. the iterator has zero items before it)

and isRemovable == false

Query Methods

public boolean hasNext( )

post: result == ( iterator == size() ) (i.e. result is false exactly when iterator is

positioned at the rear of this list)

public ItemType next ()

pre: hasNext()

post: iterator == iterator@pre + 1

and result == the item immediately preceding iterator

and isRemovable == true

public int size ()

post: result == the number of items in this list