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Java Java Data Structures - Retired Efficiency! Changing Course

Mayur Lalwani
Mayur Lalwani
1,502 Points
Posted by Mayur Lalwani
Mayur Lalwani
1,502 Points

Problem

Where's the error??

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.TreeMap;
import java.util.List;

import java.util.Map;

public class QuickFix {

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

  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
     Map<String, Video> newVideoMap = videosByTitle(course);
    if (newVideoMap.containsKey(oldTitle)) {
      newVideoMap.put(newTitle, newVideoMap.get(oldTitle));
      newVideoMap.remove(oldTitle);
    }
    newVideoMap.put(newTitle, newVideoMap.get(oldTitle));

  }

 public Map<String, Video> videosByTitle(Course course) {

    videoList = course.getVideos();
    Map<String, Video> videoMap = new TreeMap<>();
    for (Video video : videoList) {
      videoMap.put(video.getTitle(), videoList.getVideo(1));
    }
    return videoMap;
  }
}

1 Answer

Kourosh Raeen
Kourosh Raeen
23,733 Points
Kourosh Raeen
Kourosh Raeen
23,733 Points

In the videosByTitle() method you are calling getVideo() on videoList, but the List class does not have such method. Instead of videoList.getVideo(1) use video since that is the variable holding the current video in the list.

Also, in the fixVideoTitle() method you nee to use the setTitle() method from the Video class to change the title. You are only changing the title in the map. Here's my code:

import com.example.model.Course;
import com.example.model.Video;

import java.util.Map;
import java.util.TreeMap;

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.
    course.getVideos().add(1, video);
  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
    Map<String, Video> newVideoMap = videosByTitle(course);
    newVideoMap.get(oldTitle).setTitle(newTitle);
  }

  public Map<String, Video> videosByTitle(Course course) {
    Map<String, Video> videoMap = new TreeMap<>();
    for (Video video : course.getVideos()) {
      videoMap.put(video.getTitle(), video);
    }
    return videoMap;
  }
}