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Java Java Data Structures - Retired Efficiency! Changing Course

TEH HON CHEE
TEH HON CHEE
3,893 Points

Stuck on 3rd objective in Changing Course

I don't know to update the title for the videos.

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 newVideo = new Video("The Beginning Bits");
    // TODO(2):  Add to the course videos as the second video.
    course.getVideos().add(1,newVideo);
  }

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

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

}

1 Answer

Allan Clark
Allan Clark
10,810 Points

From the prompt we already know we need to use the videosByTitle() method. This method returns Map so first lets grab that Map and put it in a variable.

Map<String,Video> videos = videosByTitle(course);

Now we have a Map where the Key is the title of the video and the value is the video itself. From here we need to do two things: 1) find the video based on its current title i.e. oldTitle 2) change the title to the newTitle

We can grab the video first by using the get() method the Map class provides. Once we have the video we can use the defined setTitle() method to change the title of that video to whatever we want. Could look something like this:

Video vidToChange = videos.get(oldTitle);
vidToChange.setTitle(newTitle);

Alternatively this can all be done on one line with method chaining:

videos.get(oldTitle).setTitle(newTitle);
TEH HON CHEE
TEH HON CHEE
3,893 Points

thanks man you save the day