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Java Java Data Structures - Retired Efficiency! Changing Course

Madeline Yao
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.a{fill-rule:evenodd;}techdegree
Madeline Yao
Full Stack JavaScript Techdegree Student 9,611 Points

How to fix the title?

Hello everyone, I am having a hard time working on fixing the title and could anyone tell me where is my mistake?

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.HashMap;

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> m = videosByTitle(course); 
       Video video = m.get(oldTitle); 
       m.keySet().remove(oldTitle); 

       m.remove(oldTitle); 
       m.put(newTitle,video);
  }

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

}

1 Answer

Yanuar Prakoso
Yanuar Prakoso
15,196 Points

Hi Madeline Yao you need to edit your QuickFix.java. You previously wrote your code as:

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

import java.util.Map;
import java.util.HashMap;

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> m = videosByTitle(course); 
       Video video = m.get(oldTitle); 
       m.keySet().remove(oldTitle); 

       m.remove(oldTitle); 
       m.put(newTitle,video);
  }

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

}

you need to modify the fixVideoTitle method like this:

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

the reasoning is you do not need to modify the HashMap since it will update the title by using the setTitle method from the Video class in com.example.model.Video package as you can see in the Video.java source code.

I hope this can help you. Good day