(Maps video lesson) Example.java won't compile even though I've followed the video step by step. What's going on?

import java.util.Arrays;
import java.util.ArrayList;
import java.util.Date;
import java.util.Set;
import java.util.HashMap;
import java.util.HashSet;
import java.util.TreeSet;
import java.util.List;
import java.util.Map;
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);
    Set<String> allHashTags = new TreeSet<String>();
    Set<String> allMentions = new TreeSet<String>();
    for (Treet treet : treets) {
      allHashTags.addAll(treet.getHashTags());
      allMentions.addAll(treet.getMentions());
     }
    System.out.printf("Hash tags: %s %n", allHashTags);
    System.out.printf("Mentions: %s %n", allMentions);

    Map<String, Integer> hashTagCounts = new HashMap<String, Integer>();
      for (Treet treet : treets) {
        for (String hashTag : treet.getHashTags()) {
          Integer count = hashTagCounts.get(hashTag);
          if (count == null){
            count = 0;
          }
         count++;
         hashTagCounts.put(hashTag, count);
        }
      }
    System.out.printf("Hash tag counts: %s %n", hashTagCounts);

    Map<String, List<Treet>> treetsByAuthor = new HashMap<String, List<Treet>>();
    for (Treet treet : treets) {
      List<Treets> authoredTreets = treetsByAuthor.get(treet.getAuthor());
      if (authoredTreets == null) {
         authoredTreets = new ArrayList<Treet>();
         treetsByAuthor.put(treet.getAuthor(), authoredTreets);
      }
      authoredTreets.add(treet);
    }
    System.out.printf("Treets by author: %s %n", treetsByAuthor);
    System.out.printf("Treets by nickrp: %s %n", treetsByAuthor.get("nickrp"));

  }

}