CS 40 Fall 2007 Homework 7

1. Using Greenfoot and TextWorld, make a subclass Homework71 of Text with a method public int countWords(String wordToMatch) that returns the number of words identical to wordToMatch. For example, when you invoke countWords with the argument "Alice" (note the double quotes) on Alice in Wonderland, you should get the answer 223.

Grading criteria:

• Did you submit a class called Homework71 with a method public int countWords(String wordToMatch)?
• When invoked with a string, does it return the correct count? The grader will try a string other than "Alice".
• Partial credit if you can't figure out the parameter passing and instead implement a method that just counts "Alice".

15 points

2. Make a subclass Homework72 of Text with a method public int countPairs(String word1, String word2) that returns the number of word pairs identical to the given words. For example, when you invoke countPairs with the arguments "March" and "Hare" (note the quotes) on Alice in Wonderland, you should get the answer 16. This is a bit tricky because you get the words one at a time. The trick is to remember whether the preceding word matched. Here is an outline:

   public int countPairs(String word1, String word2)
   {
       . . .
       boolean justMatched = false;
       for (String word : getWords())
       {           
           if (word.equals(word1))
           {
               justMatched = true;
           }
           else if (word.equals(word2))
           {
               if (justMatched) // the previous one matched AND this one matched--we have a winner
               {
                   . . .
               }
               . . .
           }
           else
           {
               . . .
           }           
       }
       return . . .;
   }

Grading criteria:

• Did you submit a class called Homework72 with a method public int countMatches(String word1, String word2)?
• When invoked with two strings, does it return the correct count? The grader will strings other than "Mad" and "Hatter".

20 points

Attach just the two class files Homework71.java and Homework72.java to your submission. They will be in your TextWorld folder. Be sure to attach the .java files, not the .class files!!!