L07

Due by the end of this meeting

Starter Files:

• ArrayBag.java
• Bag.java
• TestAlls.java

Array Implementations

Activity 1

Download the class ArrayBag along with the interface Bag and the testing program TestAlls.

Revise ArrayBag by implementing the methods:

• containsAll (javadoc)
• addAll (javadoc)
• removeAll (javadoc)
• retainAll (javadoc)

The required behaviour for each method should be obvious, but if you have any questions you can consult the javadoc linked above.

Things to keep in mind:

• The argument to each method is a Collection, so it has iterator, contains and toArray methods available. You might use any/all of them in your implementations.
• The iterator method returns an Iterator. If the base type of the Collection is <? extends T> then the Iterator's base type is T. If its base type is just ?, however, the Iterator's base type is Object.
• The return value for the add/remove/retain methods is true if the contents of the Bag change, and false otherwise.
• The removeAll method should remove every copy of each of its elements from the Bag. For example, if the argument contains a 10, then every 10 should be removed from the Bag. Try to do that efficiently!
• It'd be nice if our Bag class had an iterator method that works. But it doesn't. You may use a count-controlled loop to loop thru the contents array. You'll just have to mess around with the loop control variable if you remove items.

Once you have completed the changes, your output should look like this:

Submit this/these files:

• ArrayBag.java