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Java Java Data Structures Efficiency! Changing Course

Anupam Banerjee
Anupam Banerjee
1,631 Points
Posted by Anupam Banerjee
Anupam Banerjee
1,631 Points

code checker is throwing an error on QuickFix.java problem

Please help me to understand the issue in the code - The code checker throwing an error saying - add to the list has not been used whereas I am using the add method for the array list.

private List<Video> mVideos = new ArrayList<Video>();
  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
    Video video = new Video("The Beginning Bits");
    // TODO(2):  Add the newly created video to the course videos as the second video.
    mVideos.add(video);
    course = new Course("course", mVideos);
  }
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.List;
import java.util.ArrayList;
import java.util.Map;

public class QuickFix {
  private List<Video> mVideos = new ArrayList<Video>();
  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
    Video video = new Video("The Beginning Bits");
    mVideos.add(video);
    // TODO(2):  Add the newly created video to the course videos as the second video.
    course = new Course("course", mVideos);

  }

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

  }

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

}

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

Hey Anupam, the issue is you are using add() but on the private List mVideos, not the videos from the course instance passed into the addForgottonVideo() method

  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
    Video video = new Video("The Beginning Bits");
    // TODO(2):  Add the newly created video to the course videos as the second video.
    // Get the video list from the course object
    List<Video> videos = course.getVideos();
    // Add new video as *second* video (index of 1)
    videos.add(1, video);
  }
Anupam Banerjee
Anupam Banerjee
1,631 Points
Anupam Banerjee
Anupam Banerjee
1,631 Points

Thanks Chris for the help. I understood later this point and it worked for me :)