Question

java

With the incredible royalties on your Jukebox-management code, to become a DJ. You realize that you can adapt the Jukebox code to create some sophistica software for your new career. Consider the slightly simplified versio As a DJ, you are mainly interested in the BPM (beats per minute) and rating of the songs. you decide to indulge your dream n of the book's Song class below. public class Song private String title private String artist; private int rating private int bpm; public String getArtist) return artist; ) public int getBpm) return bpm; ) public int getRating) return rating ) public String getTite) return title ) You have already adapted a lot of the Jukebox code; in particular, you have already written most of a DJ class, which has an instance variable ArrayList songlist. Now you need to write a method, makeBpmMap (), that will make it easy for you to find all the songs that have a given BPM value. gswithBPM (int bpm) that returns a collection of Songs that (c) Write a DJ instance method getSon have the given bpm value. Assume bpmMap has been filled with useful data by the makeBpmMap) method. (d) As a DJ, you also need to be able to sort a list of Songs so that you can quickly see which ones are highest rated. Without modifying the Song class, write code that will make this possible. (e) Using the code you wrote in part (d), write a DJ instance method getHighestRatedSong ( that returns the highest-rated song in songlist. (Or one of them, if there are multiple Songs with the same rating.)

Answer 1

JAVA PROGRAM

package test.song;

import java.util.ArrayList;
import java.util.HashMap;

public class TestSong {
  
   public static void main(String[] args){
      
       //song instaces created
       Song s1 = new Song("English Rock","XXX",4,100);
       Song s2= new Song("Spanish Rock","XXX",4,120);
       Song s3 = new Song("Hindi clssical Rock","",4,180);
       Song s4= new Song("Spanish Rock","XXX",4,95);
      
       DJ dj = new DJ();
       //instances are added into dj object
       dj.getSongList().add(s1);
       dj.getSongList().add(s2);
       dj.getSongList().add(s3);
       dj.getSongList().add(s4);
      
      
       HashMap<Integer, ArrayList<Song>> bpmMap = dj.getBpmMap(); //bmpMap is created
      
       System.out.println("The highest rated song is:"+ dj.getHighestRatedSong());
      
      

   }

}

--------------------------------------------------------------

package test.song;

public class Song {
   private String title;
   private String artist;
   private int rating;
   private int bpm;
  
   //constructor for Song
   public Song(String title, String artist, int rating, int bpm) {
       this.title = title;
       this.artist = artist;
       this.rating = rating;
       this.bpm = bpm;
   }
   public String getTitle() {
       return title;
   }
   public String getArtist() {
       return artist;
   }
   public int getRating() {
       return rating;
   }
   public int getBpm() {
       return bpm;
   }
  
   //overridden to string method
   @Override
   public String toString() {
       return "Song [title=" + title + ", artist=" + artist + ", rating=" + rating + ", bpm=" + bpm + "]";
   }
  
  
  

}

--------------------------------------------------------------------------------

package test.song;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;

public class DJ {
  
   private ArrayList<Song> songList = null;
  
   private HashMap<Integer,ArrayList<Song>> bpmMap = null;
  
   //trough DJ constructor songlist is initialized
   public DJ(){
       songList = new ArrayList<Song>();
   }
  
  
  
   public ArrayList<Song> getSongList() {
       return songList;
   }

   public void setSongList(ArrayList<Song> songList) {
       this.songList = songList;
   }

   public HashMap<Integer, ArrayList<Song>> getBpmMap() {
       return bpmMap;
   }

   public void setBpmMap(HashMap<Integer, ArrayList<Song>> bpmMap) {
       this.bpmMap = bpmMap;
   }

   /**
   * this mehod will return list of songs by bmpRate
   * @param bpmRate
   * @return
   */
   public ArrayList<Song> getSongsWithBpm(int bpmRate){
           return this.bpmMap.get(bpmRate);
   }
  
   /**
   * sort the songs based on highest ratings
   * h
   */
   private void sortSongsByRating(){
       Collections.sort(songList, new Comparator<Song>(){

           @Override
           public int compare(Song s1, Song s2) {
               if(s1.getRating() > s2.getRating()){
                   return 1;
               }else if(s1.getRating() < s2.getRating()){
                   return -1;
               }else{
                   return 0 ;
               }
           }
          
       });
   }
  
   /**
   * THIS WILL CALL sortSongsByRating
   * and take the first Song object
   * @return
   */
   public Song getHighestRatedSong(){
       sortSongsByRating();
      
       return this.songList.get(0);
   }
  
  

}

====================================

OUTPUT

The highest rated song is:Song [title=English Rock, artist=XXX, rating=4, bpm=100]