Lab 16: Iterator

For this lab you will implement a WordList which is an infinitely expanding container of Strings. The WordList class will keep an array of Strings which starts at a size of 2 (the first array created is of size 2) but then doubles in size whenever the user of the class tries to add an element which would not fit in the current wordlist. For example, the first time it doubles will be when trying to add the third word, then on the fifth, then on the ninth, and so on.

Specifically, WordList will implement the following methods:

• add(String w): adds the string w to the word list, and expands the size of the underlying array if needed, by doubling its size. It returns the WordList.
• size(): returns the number of words in the WordList
• length(): returns the length of the array
• toString(): all the words, separated by spaces.

Furthermore, the WordList implements the following interface:

public interface Iterator {

 /**
  * Resets the iterator to point to the first word.
  */
 public void resetIterator();
 
 /**
  * Returns the next word. If we are beyond the end then return null.
  * Also moves the iterator to the next word.
  * @return the next word or null.
  */
 public String getNext();
 

 /**
  * @return true if there are still words to iterate over. 
  *   false if we have reached the end
  */
 public boolean hasNext();
}

For example, the following code:

public static void main(String[] args) {
  //Test adding words
  WordList l = new WordList();
  System.out.println("There are " + l.size() + " words.");
  System.out.println("The words array is of length " + l.length() + ".");
  l.add("We").add("are").add("the").add("priests").add("of");
  l.add("The").add("Temples").add("of").add("Syrinx");
  System.out.println(l);
  System.out.println("There are " + l.size() + " words.");
  System.out.println("The words array is of length " + l.length() + ".");
  l.add("Our").add("great").add("computers").add("fill").add("the").add("hallowed").add("halls");
  System.out.println(l);
  System.out.println("There are " + l.size() + " words.");
  System.out.println("The words array is of length " + l.length() + ".");
  //Test REALLY big word lists
  for (int i = 0; i < 10000000; i++) {
   l.add("Rush");  
  }
  System.out.println("There are " + l.size() + " words.");
  System.out.println("The words array is of length " + l.length() + ".");
  
  //Test the iterator
  System.out.println("--Testing the iterator");
  l = new WordList();
  l.add("We").add("have").add("assumed").add("control");
  l.add("There").add("is").add("trouble").add("with").add("the").add("trees");
  l.resetIterator();
  while (l.hasNext()){
   String w = l.getNext();
   System.out.println(w);
  }
 }

prints out

There are 0 words.
The words array is of length 2.
We are the priests of The Temples of Syrinx 
There are 9 words.
The words array is of length 16.
We are the priests of The Temples of Syrinx Our great computers fill the hallowed halls 
There are 16 words.
The words array is of length 16.
There are 10000016 words.
The words array is of length 16777216.
--Testing the iterator
We
have
assumed
control
There
is
trouble
with
the
trees