How to retrieve a String from a different class file and then add that String to an Array then remove certain words if they appear more than once

Question

I've been stuck on this problem for a few days and can't find any answers to this question. It's slowly driving me insane. I need to make a two methods, one that add that word to the Array Word[] words and one that removes it if the word occurs more than once. Sadly, every time I try to use .add or anything of the sort it doesn't work. I am so confused.

WordBagClient

 public class WordBagClient {

  public static void main(String[] args) throws IOException {
  System.out.println("PMJ's WordBagClient ...");
  String filename;
  if(args.length > 0) {   // Use run-time first argument value
     filename = args[0];
  } 
  else {   // Prompt user to enter name of data file and store response
     System.out.print("Enter name of input file:");
     Scanner keyboard = new Scanner(System.in);
     filename = keyboard.nextLine();
  }
  // Establish Scanner object that can read from the input data file.
  Scanner input = new Scanner(new File(filename));

  WordBag wordBag = new WordBag(256);

  String s;
  // Add each of the words until a blank line is encountered
  do {
     s = input.nextLine();
     System.out.println(s);
     if(s.length() > 0) {
        addTask(s,wordBag);
     }
  } while (s.length() > 0);
  printWordBag(wordBag);
  // Remove an instance of each of the words until a second blank line is encountered
  do {
     s = input.nextLine();
     System.out.println(s);
    if(s.length() > 0) {
      //removeTask(s,wordBag);
     }
  } while (s.length() > 0);
  printWordBag(wordBag);
  }

   static void addTask(String s, WordBag wordBag) {
   Scanner wordScanner = new Scanner(s);
   while(wordScanner.hasNext()) {
     String string = wordScanner.next();
     String word = Word.wordOf(string);
     wordBag.add(new Word(word));
  }
  }

  static void removeTask(String s, WordBag wordBag) {
  Scanner wordScanner = new Scanner(s);
   while(wordScanner.hasNext()) {
     String string = wordScanner.next();
     String word = Word.wordOf(string);
     Word object = new Word(word);
     while(wordBag.multiplicityOf(object) > 0) { 
        wordBag.remove(object);
     }
  }
  }

  static void printWordBag(WordBag wordBag) {
  System.out.println("The word bag now contains:");
  System.out.println("--------------------------");
  System.out.println(wordBag.toString());
  System.out.println("--------------------------");
  /*
  wordBag.reset();
  while(wordBag.hasNext()) {
     System.out.print(wordBag.next());
     if(wordBag.hasNext()) { System.out.print(","); }
  }
  System.out.println("\n"+"--------------------------");
  */
 }
 }

This is my WordBag.java

public class WordBag  {

public static final int DEFAULT_CAPACITY = 8;   //Default number of distince   words
                                               //allowed in a bag.

private int capacity;      //The capacity of this instance's private arrays
private Word[] words;      //The array to hold the words
private int[] counts;      //The array to hold the corresponding counts
private int nextIndex;     //Indicates the next available element position


public WordBag() {
this.words = new Word[DEFAULT_CAPACITY];
this.counts = new int[DEFAULT_CAPACITY];

}


public WordBag(int specifiedCapacity) { 
if (capacity>-1){
this.capacity = specifiedCapacity;
this.words = new Word[capacity];
this.counts = new int[capacity];
}else{
this.capacity = DEFAULT_CAPACITY;
this.words = new Word[DEFAULT_CAPACITY];
this.counts = new int[DEFAULT_CAPACITY];


}
nextIndex = 0;


}


public boolean has(Word word) { 
boolean dog = false;
do{
if(words[nextIndex].equals(word)){
return dog = true;

}else{
nextIndex++;
}


 }while(nextIndex<=capacity && words[nextIndex]!=word);


  return dog;
 }   


  public int multiplicityOf(Word word) {  //Stub!!!
  int result=0;
  do{
  words[nextIndex].equals(word);
   result = result+1;
  }while(nextIndex<=capacity && words[nextIndex]!=word);  
  return result;
  }   


  public void add(Word word) {  //Stub!!!

  do{

  words[nextIndex]=(word);

  }while(nextIndex<=capacity && words[nextIndex]!=word); 
  nextIndex++;  
  }


  public void remove(Word word) {  //Stub!!!

  do{
  if(multiplicityOf(word)>0){
  word=null;

  }else{
  word=word;
  }
  }
  while(nextIndex<=capacity && words[nextIndex]!=word);



  }


   private final String COMMA = ",";


  public String toString() {  //Stub!!!
   String result = "";

   result = Arrays.toString(words);
  return result;
  }





}

This is my Word Class

public class Word  {

public static final String SYMBOLS = "`~!@#$%^&*()-_=+[{]}\\|;:'\",<.>/?";

private String word = "";

public Word(String string) {
  String word = Word.wordOf(string);
  if(Word.isWord(word)) {
     this.word = word;
  }
}


 public String toString() {
  return word;
 }


  public boolean equals(Word that) {
  return this.compareTo(that) == 0;
 }


  public int compareTo(Word that) {
  return this.toString().compareTo(that.toString());
 }



  public static String wordOf(String s) {
  String result = "";
  //Trim of leading and trailing whitespace
  s = s.trim();
  //Scan over leading symbols
  int start;
  for(start=0; (start<s.length()) && (SYMBOLS.indexOf(s.charAt(start))>=0);  start++) {
  }
  //Scan over trailing symbols
  int stop;
  for(stop=s.length()-1; (stop > start) &&       (SYMBOLS.indexOf(s.charAt(stop))>=0); stop--) {
  }
  //Isolate what is left in the middle
  if(start <= stop) {
     result = s.substring(start,(stop+1));
  }
  //Return
  return result;
 }


 public static boolean isWord(String s) {
  s = s.trim();
  return (s.length() > 0) && (s.equals(Word.wordOf(s)));   
}
}