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Java Java Data Structures Efficiency! Changing Course

Juan Santiago
Juan Santiago
3,766 Points
Posted by Juan Santiago
Juan Santiago
3,766 Points

Problems with the final step of the final challenge :/

The code compiles properly, but an error appears saying "Are you sure you updated the video's title?" It seems obvious that the bug is in the fixVideoTitle method, but I don't know why it doesn't work that way D:

Thanks for your help...

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;
import java.util.List;
import java.util.*;

public class QuickFix {

  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.
List<Video> videoList = course.getVideos();
    videoList.add(1, video);
  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
        if(videosByTitle(course).containsKey(oldTitle)){
          videosByTitle(course).put(newTitle,videosByTitle(course).get(oldTitle));
           videosByTitle(course).remove(oldTitle);
    }
  }

  public Map<String, Video> videosByTitle(Course course) {
     Map<String, Video> sortedVideos = new TreeMap<String,Video>();
    // For each video in the course:
    // Set the key to the video title, and the value as the video reference
    for(Video video: course.getVideos()) {
          sortedVideos.put(video.getTitle(),video);
    }
      return sortedVideos;
  }

}

1 Answer

Ryan Ruscett
Ryan Ruscett
23,309 Points
Ryan Ruscett
Ryan Ruscett
23,309 Points

Hey,

You don't need to actually do all you are doing in the fixVideoTitle method. (I just tested this and it works)

Get ride of all whatever this is. if(videosByTitle(course).containsKey(oldTitle)){ videosByTitle(course).put(newTitle,videosByTitle(course).get(oldTitle)); videosByTitle(course).remove(oldTitle);

All you need to do is create a map Map<String, Video> someNewMap = videosByTitle(course);

get the old movie title from the video Video video = someNewMap .get(oldTitle);

and then set it. video.setTitle(newTitle);

Collectivity, I would removing the code you have for the FixVideoTitle method and replace it with what I have below.

Map<String, Video> someNewMap = videosByTitle(course); Video video = someNewMap .get(oldTitle); video.setTitle(newTitle);

You can leave all the other methods alone. I know you passed step 2 with this, but it wont work for step three.

Let me know if that helps you out! Thanks!

Juan Santiago
Juan Santiago
3,766 Points
Juan Santiago
Juan Santiago
3,766 Points

Thank you, your answer pointed me in the right direction, but it has a little error:

Instead of 

Video video = someNewMap.get(oldTitle);

is

Video video = videosByTitle(course).get(oldTitle);

Otherwise you'll get a compiler error saying that "someNewMap.get(oldTitle);" can't be converted to a "Video" object. Therefore, the final version of fixVideoTitle method is:

 public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
              Map someNewMap = videosByTitle(course); 
              Video video = videosByTitle(course).get(oldTitle);
              video.setTitle(newTitle);

Again, thank you so much, without your help I wouldn't be able to find the way to complete the task.