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Java Java Data Structures Efficiency! Changing Course

Posted by Nishant Raj
Nishant Raj
1,552 Points

Getting Bummer

I tried with this code but getting error: Hmmm...I found the old value 'Typo Casting' and the new value 'Type Casting'. You should 'get' the video from the map and update the video using 'setTitle'

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;
  }

  public void addVideo(int index, Video video){
    mVideos.add(index, video);
  }
}
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 {
  private Map<String, Video> byTitle  = new HashMap<String, Video>();
  private Map<String, Video> fixTitle = new HashMap<String, Video>();
  public void addForgottenVideo(Course course) {
    Video video = new Video("The Beginning Bits");
    course.addVideo(1, video);
  }

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

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {  
   fixTitle = videosByTitle(course);
    if(fixTitle.containsKey(oldTitle)){
      Video video = fixTitle.get(oldTitle);
       video.setTitle(newTitle);
    }
  }

}

1 Answer

David Garner
David Garner
4,181 Points
David Garner
David Garner
4,181 Points

Your code looks good for the most part, if I am not mistaken you only need to create one Map.

This is how I would write it:

 public Map<String, Video> videosByTitle(Course course){
  Map<String, Video> byTitle  = new HashMap<String, Video>();  //create the map locally within the function
  for(Video video : course.getVideos()){
      byTitle.put(video.getTitle(), video);
    }
    return byTitle;
  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {  
   Map<String, Video> videoMap = videosByTitle(course);

   if(videoMap.containsKey(oldTitle)){
      Video video = videoMap.get(oldTitle);
       video.setTitle(newTitle);
    }
  }

I would delete theses lines at the top of your QuickFix.java file

private Map<String, Video> byTitle  = new HashMap<String, Video>();
private Map<String, Video> fixTitle = new HashMap<String, Video>();