Illegal start of 'for'??

Did you complete this challenge? I've stuck with it.

public Set<String> getAllAuthors() { Set<String> allAuthors = new TreeSet<String>(); for (??? ???: ???) { allAuthors.addAll(???.getAuthor()); } return allAuthors;

Need something like that?

Its close, you need to make sure you define what the sets are holding like

Set<SomeType> someSet = new TreeSet<>();

as well as in your returntype. For the for loop, consider what you're looping over, you need to define it as

for(Type variable: someList)

Got this:

public Set<String> getAllAuthors() {
    Set<String> allAuthors = new TreeSet<String>();
    for (Blog post: posts) {
      allAuthors.addAll(post.getAuthor());
    }
     return allAuthors;

But an error occured:

./com/example/Blog.java:21: error: cannot find symbol
    for (Blog post: posts) {
                    ^
  symbol:   variable posts
  location: class Blog
./com/example/Blog.java:22: error: cannot find symbol
      allAuthors.addAll(post.getAuthor());
                            ^
  symbol:   method getAuthor()
  location: variable post of type Blog
Note: JavaTester.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
2 errors

First, the posts are in the member variable mPosts. Second, you might want to use Set.add instead of Set.addAll since you're only adding a single item and not a collection.

I did it, man! Thank you very much!

Haha, that is the only bit of code I have written, the only bit of code missing is String after Set and TreeSet, it hasn't pasted for some reason. The challenge was to add a method to this Blog class that takes the author from each blogpost and puts them into an alphabetically ordered list using the java.util.Set interface. The getAuthor method is in the BlogPost class. To my mind this code is saying create a new alphabetically ordered list called getAllAuthors, then for each blogpost in Blog (a list of blogposts) get the author and add it to the getAllAuthors list, hence, completing the challenge. Clearly my understanding isn't quite what it should be yet!

I solve it :3

 public Set<String> getAllAuthors() {
    Set<String> allAuthors = new TreeSet<String>();
    for (BlogPost post: mPosts) {
      allAuthors.add(post.getAuthor());
    }
     return allAuthors;
}