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Java Java Data Structures - Retired Efficiency! Changing Course

Daniel Paradiso
PLUS
Daniel Paradiso
Courses Plus Student 3,915 Points
Posted by Daniel Paradiso
Daniel Paradiso
Courses Plus Student 3,915 Points

I'm having trouble remembering how to get a map to work. Am i supposed to get the name from course (mName)?

Am i supposed to get the string from course (mName), then make a List of video titles to loop through? The code is unfinished and I didn't update the java.util for the hashmap. Any help appreciated.

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;

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) {

  }

  public Map<String, Video> videosByTitle(Course course) {
    Map<String, Video> videosByTitle = new HashMap<>();
    for (Video video = mTitle) {
      List<Video> videoTitles = videosByTitle.get(video.getTitle());
      if (videoTitles == null) {
        videoTitles = new ArrayList<>();
        videosByTitle.put(
      }
    }
    return null;
  }

}
Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points

for modern generics, you typically specify a type in both the creation and declaration (however, there is such a thing as a raw type). With looping, you can use : with collections (read ":" as "in"), while "value= " style does show up with iterators. If you have any questions about my posted answer, feel free to ask, but i assumed you'd react to it with a meaningful declaration of 'oh' and understand immediately.

2 Answers

Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points 
public Map<String, Video> videosByTitle(Course course) {
    Map<String, Video> m = new HashMap<String, Video>();
    for(Video v: course.getVideos())
    {
      m.put(v.getTitle() ,v);
    }

    return m;
  }
Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points

oh, you might need to import HashMap.

Daniel Paradiso
PLUS
Daniel Paradiso
Courses Plus Student 3,915 Points
Daniel Paradiso
Daniel Paradiso
Courses Plus Student 3,915 Points

Thank you for your answer. I have a terrible habit of making things way more complicated than they need to be.... I think I need a sticky note too. (K.I.S.S.)