Bag Class Diagram

Bag Class Specification

Invariant

A Bag<ItemType> object...

- is a container of zero or more other objects

- is capable of storing anything that conforms to the instantiated argument for ItemType (This instantiated argument can be any class name.)

Constructor Method

public Bag<ItemType> ( )

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

Update Methods

public void insert ( ItemType z)

post: this == this@pre with z inserted

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

public void remove ()

pre: size() > 0

post: this == this@pre with one item removed

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

Query Methods

public int size ()

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

public ItemType item ( )

pre: size() > 0

post: result == one of the items from this Bag