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 Efficiency! Changing Course

Aaron Goodman
Aaron Goodman
3,953 Points

I'm unsure of how to add to the course list. mVideos is private to Course, and in Course.java, there are only getters.

Unless I change mVideos to protected, I don't know how I'm going to change it from another class. But that is outside the scope of the instructions.

Please help!!! -Aaron

com/example/model/Course.java
package com.example.model;

import java.util.List;

public class Course {
  private String mName;
  private List<Video> mVideos; 

  public Course(String name, List<Video> videos) {
    mName = name;
    mVideos = videos;
  }

  public String getName() {
    return mName;
  }

  public List<Video> getVideos() {
    return mVideos;
  }

}
com/example/model/Video.java
package com.example.model;

public class Video {
  private String mTitle;

  public Video(String title) {
    mTitle = title;
  }

  public String getTitle() {
    return mTitle;
  }

  public void setTitle(String title) {
    mTitle = title;
  }

}
QuickFix.java
import com.example.model.Course;
import com.example.model.Video;

import java.util.Map;

public class QuickFix {

  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
    Course mCourse;
    mCourse = course;
    Video newVideo = new Video("The Beginning Bits");
    // TODO(2):  Add the newly created video to the course videos as the second video.
      mVideos.add(1,newVideo);
  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {

  }

  public Map<String, Video> videosByTitle(Course course) {
    return null;
  }

}

1 Answer

The basic problem is, as you indicate, you are calling the add method on mVideos, which is a private instance variable. One way around this, as you indicate, is to add a public method in Course to add videos:

   public void addVideos(int index, Video x) {
      mVideos.add(index, x);
   }

Now, back in QuickFix, you call the addVideos() method on course -- the Course object which is a formal parameter of your addForgottenVideo() method, not on mVideos:

course.addVideos(1, newVideo);

With these changes it compiles fine.