Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Data Structures - Retired Exploring the Java Collection Framework Maps

for-each not applicable to expression type

So i am trying to print every Author's treet separately here instead the messy way Craig showed So i used a for-each loop to loop through the map

And then i also tried to loop through that specific Key's value to print every treet separately Since the value of the Map is a List of Treet, when entry.getValue() is called it must return a list of Treet right ? so i can loop through every treets

    Map<String, List<Treet>> treetsByAuthor = new HashMap<String, List<Treet>>();
    for (Treet treet : treets) {
      List<Treet> authoredTreets = treetsByAuthor.get(treet.getAuthor());
      if (authoredTreets == null) {
        authoredTreets = new ArrayList<Treet>();
        treetsByAuthor.put(treet.getAuthor(), authoredTreets);
      }
      authoredTreets.add(treet);
    }

for (Map.Entry entry : treetsByAuthor.entrySet()) {
      System.out.printf("Treets by %s are : \n", entry.getKey());
      for(Treet treet : entry.getValue()) {
        System.out.println(treet);
      }
    }

But instead i am getting this error

Example.java:62: error: for-each not applicable to expression type                                                                                                                    
      for(Treet treet : entry.getValue()) {                                                                                                                                           
                                      ^                                                                                                                                               
  required: array or java.lang.Iterable                                                                                                                                               
  found:    Object                                                                                                                                                                    
1 error

2 Answers

The only thing you need to change is to specify the types of the entry (i.e <String, List<Treet>> in this example)

for (Map.Entry<String, List<Treet>> entry : treetsByAuthor.entrySet()){

I hope this helps.

It worked thanks :)