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 Efficiency! Add tags to a course

Enyang Mercy
Enyang Mercy
Courses Plus Student 2,339 Points

UI initialize mTags in the constructor

Need Help !!! I keep having errors. Can someone help with the proper initialization,please.

package com.example.model;

import java.util.List;
import java.util.Set;

public class Course {
  private String mTitle;
  private Set<String> mTags;

  public Course(String title) {
    mTitle = title;
    mTags = new mTags<String, String>();
    // TODO: initialize the set mTags

  public void addTag(String tag) {
    // TODO: add the tag

  public void addTags(List<String> tags) {
    // TODO: add all the tags passed in

  public boolean hasTag(String tag) {
    // TODO: Return whether or not the tag has been added
    return false;

  public String getTitle() {
    return mTitle;


2 Answers

Hi there,

You want to create a new Set but, because a Set is abstract, you should use a HashSet. So, first import the Hashset at the top of the class. Then you want to assign a new HashSet of strings into mTags - remember, you're calling the constructor so you'll need some parentheses too.

Let me know how you get on.


Good work! :+1: :+1: :+1: