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Java Java Data Structures - Retired Efficiency! Changing Course

not able to update key in hashmap

I am not able to update key in HashMap,please suggest

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;
import java.util.List;
import java.util.Iterator;
import java.util.Map.Entry;

public class QuickFix {

  public void addForgottenVideo(Course course) {
    // TODO(1):  Create a new video called "The Beginning Bits"
    Video vd = new Video("The Beginning Bits");

    // TODO(2):  Add the newly created video to the course videos as the second video.
    course.getVideos().add(1,vd);

  }

  public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
    Map<String,Video> map = new HashMap<String,Video>();
  map =videosByTitle(course);
    Iterator it = map.entrySet().iterator();
    Video vd = null;
    while(it.hasNext()){
      Entry item =(Entry) it.next();
      if(item.getKey().equals(oldTitle) ){
        vd =(Video) item.getValue();
       it.remove(); 
      }
    }

     map.put(newTitle,vd);



  }

  public Map<String, Video> videosByTitle(Course course) {
    Map<String,Video> map = new HashMap<String,Video>();
     List<Video> videoList = course.getVideos();
    String title = null;
    for(Video vd : videoList){
      title = vd.getTitle();
      map.put(title,vd);
    }

    return map;
  }

}

1 Answer

Umesh Ravji
Umesh Ravji
42,386 Points

Hi Prabhat, I think you may have misunderstood the question. The fixVideoTitle() method simply requires you to find the video object that has the title of oldTitle and update the title to be newTitle.

public void fixVideoTitle(Course course, String oldTitle, String newTitle) {
  Video video = this.videosByTitle(course).get(oldTitle); // obtain video using previously created method
  if (video != null) {
    video.setTitle(newTitle);
  }
}

Thanks Umesh :)