Why does my code not compile?

import java.io.Serializable;
import java.util.Date;
import java.util.ArrayList;
import java.util.Arrays; 
import java.util.List; 
import com.teamtreehouse.Treet;
import com.teamtreehouse.Treets;


public class Example {

  public static void main(String[] args) {
    Treet[] treets = Treets.load();
    System.out.printf("There are %d treets. %n",
                     treets.length);
    Treet[] originalTreet = treets[0]; 
    System.out.println("Hastags"); 
    for (String hashtag: getWords.getHashTags()) {
     System.out.println(hashtag);  
    }

  }

}

package com.teamtreehouse;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays; 
import java.util.List; 
import java.util.Date;



public class Treet implements Comparable, Serializable, List {
  private static final long serialVersionUID = 7146681148113043748L;
  private String mAuthor;
  private String mDescription;
  private Date mCreationDate;

  public Treet(String author, String description, Date creationDate) {
    mAuthor = author;
    mDescription = description;
    mCreationDate = creationDate;
  }

  @Override
  public String toString() {
    return String.format("Treet:  \"%s\" by %s on %s", 
                         mDescription, mAuthor, mCreationDate);
  }

  @Override
  public int compareTo(Object obj) {
    Treet other = (Treet) obj;
    if (equals(other)) {
      return 0;
    }
    int dateCmp = mCreationDate.compareTo(other.mCreationDate);
    if (dateCmp == 0) {
      return mDescription.compareTo(other.mDescription);
    }
    return dateCmp;
  }

  public String getAuthor() {
    return mAuthor;
  }

  public String getDescription() {
    return mDescription;
  }

  public Date getCreationDate() {
    return mCreationDate;
  }

  public List<Strings> getWords() {
   String words[] = mDescription.toLowerCase().split("[^\\w#@']+"); 
      return Arrays.asList(words); 
  }

  private List<Strings> getWordsPrefixWith(String prefix) {
    List<String> results =  new ArrayList<String>();
    for (String word: getWords()) {
      if (word.startsWith(prefix)) {
        results.add(word);  
      }
    }
   return results; 
  }

 private List<Strings> getHashTags() {
   return getWordsPrefixWith("#");
  }

   public List<Strings> getMentions() {
    return getWordsPrefixWith("@");
   }




}