L04a

Due by the end of Wednesday, January 31

Starter Files:

• ArrayBag.java
• Bag.java
• TestAddAll.java
• TestRemove.java

Array Implementations

Activity 1

Complete the addAll method in the class ArrayBag (provided). It is given a Collection (a List or Set or possibly even a Bag) and its job is to add every element from that Collection to this Bag. For example, if this Bag starts with [A, B] in it, and is asked to add everything from the Set {E, T, A}, then it will end up with [A, B, E, T, A] in it.

Its return value says whether anything was added to the Bag. (That is, did the number of things in the Bag change?)

Test your code using the TestAddAll program provided. You should see the following output:

OK so far! [10, 20, 30, 40, 50, 40, 30] OK so far! [10, 20, 30, 40, 50, 40, 30]

Activity 2

In class we will see (or possibly have seen) that removing an element from the middle of a Bag is easy because we can move the last element of the array down to fill in the hole.

That doesn't work for a List, where the order of the elements is important. We're going to take a look at how ArrayList's remove method might work.

Download the class TestRemove. In it, write the method int remove(String[] arr, int len, String toRemove) that removes the first occurrence of toRemove from arr and moves all the following elements up to fill in the hole. (Remember to null out the location you moved from.)

• The parameter len says how many of the elements of arr were in use (so like numInBag in the ArrayBag class).
• The method returns the new number of elements in use (that is, one less than len if toRemove was found, and the same as len if it was not.

Run the TestRemove program. You should see the following output:

[These, are, my, words, and, my, words, are, these] [These, my, words, and, my, words, are, these, null] [These, words, and, my, words, are, these, null, null] [These, words, and, my, words, are, these, null, null] [These, words, and, my, words, are, null, null, null]

Your grade will be based on the following rubric:

• 0 points: it does not compile; or does neither activity is complete and correct; or either activity uses methods or controls other than those required.
• 1 point: one of the two activities is complete and correct; or both activities are complete and correct but the program style is incorrect.
• 2 points: both activities are complete and correct, and the program uses correct style.

Submit this/these files:

• ArrayBag.java
• TestRemove.java