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

Posted by k doshi
k doshi
128 Points

Can anyone explain this code? List based on Author name?

Map<String, List<Treet>> treetsByAuthor = new HashMap<String,List<Treet>>(); for(Treet treet: treets){ List<Treet> authoredTreets = treetsByAuthor.get(treet.or()); 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"));
}

Steven Parker Brendan Whiting Rob Bridges Steve Hunter Amanda Lam Chris Freeman