Question

Read Carefully:

You are given a class called Record, which defines an audio (pre-CD or MP3) Record. If you need to, you can add methods to this class.

You are to write a class called Jukebox, which holds a number of Records.     Jukebox can use either an ArrayList or a Vector to store its data (Records).   This will be referred to as AL or V from here on.

Your Jukebox class should implement JukeInterface, which is also in this Minilab’s folder.   It will tell what methods must be implemented (and the comments describe how the methods should work).

You can write Jukebox in either one of two ways:

1)Jukebox can be a subclass of AL or V (using “implements”).    This makes all of the AL or V methods automatically inherited by Jukebox.    So in the Jukebox code, you can access the .indexOf method (for example) by calling indexOf or this.indexOf.    This is because it is the Jukebox’s own method.  

The disadvantage of this is that outside programs (like the tester) can call Jukebox’s methods and also call the AL or V methods.

2)Jukebox can be a class that has an AL or V as part of its data.   In the Polymorphism Minilab, this is how Course was implemented – it had an Array as part of its data.   If you do it this way, you should

-declare the AL or V as data and then

-create it (with a “new” statement) in the constructor.  

The advantage is that outside programs (like the tester) can now only “see” the Jukebox’s methods.

In addition, you have 2 other requirements:

1)You should use Generics to define your AL or V.    In your program, it will only hold Records.

2)You should not traverse the AL or V to try to “do things yourself.”    You can look up built-in AL or V methods which will do everything you need. NOTE:   In order for some built-in AL or V methods to work correctly, you will have to add a specific method to Record (as described in class).

A driver program called JukeTester.java is provided.    There are some subtle relationships between the Record class and Jukebox’s AL or V.   I have some explanations as .txt files, but try them yourself first.

Comments and formatting:   Please put in an opening comment that briefly describes the purpose of your program. Each constructor/method should haYou are given a class called Record, which defines an audio (pre-CD or MP3) Record. If you need to, you can add methods to this class.

You are to write a class called Jukebox, which holds a number of Records.     Jukebox can use either an ArrayList or a Vector to store its data (Records).   This will be referred to as AL or V from here on.

Your Jukebox class should implement JukeInterface, which is also in this Minilab’s folder.   It will tell what methods must be implemented (and the comments describe how the methods should work).

You can write Jukebox in either one of two ways:

1)Jukebox can be a subclass of AL or V (using “implements”).    This makes all of the AL or V methods automatically inherited by Jukebox.    So in the Jukebox code, you can access the .indexOf method (for example) by calling indexOf or this.indexOf.    This is because it is the Jukebox’s own method.  

The disadvantage of this is that outside programs (like the tester) can call Jukebox’s methods and also call the AL or V methods.

2)Jukebox can be a class that has an AL or V as part of its data.   In the Polymorphism Minilab, this is how Course was implemented – it had an Array as part of its data.   If you do it this way, you should

-declare the AL or V as data and then

-create it (with a “new” statement) in the constructor.  

The advantage is that outside programs (like the tester) can now only “see” the Jukebox’s methods.

In addition, you have 2 other requirements:

1)You should use Generics to define your AL or V.    In your program, it will only hold Records.

2)You should not traverse the AL or V to try to “do things yourself.”    You can look up built-in AL or V methods which will do everything you need. NOTE:   In order for some built-in AL or V methods to work correctly, you will have to add a specific method to Record (as described in class).

A driver program called JukeTester.java is provided.    There are some subtle relationships between the Record class and Jukebox’s AL or V.   I have some explanations as .txt files, but try them yourself first.

Comments and formatting:   Please put in an opening comment that briefly describes the purpose of your program. Each constructor/method should have a brief descriptive comment.   Also, please be sure that your indenting is correct and that your variable names are meaningful.ve a brief descriptive comment.   Also, please be sure that your indenting is correct and that your variable names are meaningful.

Some Code and Tester:

Record:

//This class describes a (pre-CD) record

public class Record
{
        //data
        private String title;
        private String artist;

        //constructor
        public Record(String theTitle, String theArtist)
        {
                this.title = theTitle;
                this.artist = theArtist;
        }

}

Jukebox class:

public interface JukeInterface
{
        //insert(Record aRecord) - inserts a Record at the last position in the jukebox
        public void insert(Record aRecord);

        //insert(int slot, Record aRecord) - inserts a Record into a specific slot in the jukebox
        public void insert(int slot, Record aRecord);

        //remove(Record aRecord) - removes a Record from the jukebox.   If the
        //                         Record does not exist, it is unchanged.
        public boolean remove(Record aRecord);

        //contains(Record aRecord) - returns true if the jukebox contains the Record
        public boolean contains(Record aRecord);

        //findSlot(Record aRecord) - returns the slot that has the Record (-1 if not there)
        public int findSlot(Record aRecord);

        //random() - returns a Record, chosen at random
        //                                      FOR EXAMPLE, to generate a random int between 0 and 9 (inclusive)
        //                                              1.  create a new instance of Random -->  Random gen = new Random();
        //                                              2.  tell it to return a random int between 0 and 9 (inclusive) --> int theRand = gen.nextInt(10);
        //                                      OR: to generate a random int between 0 and 9 (inclusive), use (int)(Math.random()*10);
        public Record random();

        //toString() - returns this jukebox's representation as a String.  Should show the contents.
        public String toString();
}

Tester:

//This class will test the Jukebox and Record classes which were parts
//of the ArrayLists, Vectors minilab

public class JukeTester
{
        public static void main(String[] args)
        {
                //testRecord will be used for queries
                Record testRecord;

                System.out.println("------- Creating a new Jukebox and inserting only 1 Record");
                Jukebox myJukebox = new Jukebox();
                myJukebox.insert(new Record("Kokomo", "The Beach Boys"));

                //print it (using S.O.P.)
                System.out.println("\n------- printing the Jukebox (tests Jukebox's and Record's toString())");
                System.out.println("Jukebox now contains: " + myJukebox);

                //tell it to return 5 random records
                System.out.println("\n------- telling it to return 5 random Records (should all be the same)");
                System.out.println("\nA random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());

                System.out.println("\n------- creating a different new Jukebox and telling it to insert 5 Records");
                myJukebox = new Jukebox();
                myJukebox.insert(new Record("Kokomo", "The Beach Boys"));
                myJukebox.insert(new Record("Wooly Bully", "Sam the Sham & the Pharaohs"));
                myJukebox.insert(new Record("Mustang Sally", "Wilson Pickett"));
                myJukebox.insert(1, new Record( "Great Balls of Fire", "Jerry Lee Lewis"));
                myJukebox.insert(0, new Record("I Feel Good", "James Brown"));

                //print it (using S.O.P.)
                System.out.println("\n------- printing the Jukebox (tests Jukebox's and Record's toString())");
                System.out.println("Jukebox now contains: " + myJukebox);

                //tell it to return 5 random records
                System.out.println("\n------- telling it to return 5 random Records (the random Records will vary)");
                System.out.println("\nA random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());
                System.out.println("A random Record is: " + myJukebox.random());

                //ask it if it contains "Kokomo" by The Beach Boys
                System.out.println("\n------- asking if it contains \"Komomo\" by the Beach Boys");
                System.out.println("            (tests existance of .equals that receives an Object)");
                testRecord = new Record("Kokomo", "The Beach Boys");
                System.out.println("\nDoes it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

                //ask it if it contains "Kokomo" by The Beach Boys (with different Strings for title/artist)
                System.out.println("\n------- asking if it contains \"Komomo\" by the Beach Boys");
                System.out.println("            (test created with title/artist in different memory locations)");
                System.out.println("            tests whether Records .equals usings String's .equals when comparing title and artist)");
                testRecord = new Record(new String("Kokomo"), new String("The Beach Boys"));
                System.out.println("\nDoes it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

                //ask it if it contains "Mustang Sally" by the Commitments
                System.out.println("\n------- asking if it contains \"Mustang Sally\" by the Commitments");
                testRecord = new Record("Mustang Sally", "The Commitments");
                System.out.println("Does it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

                //ask it if it contains "Its Too Late" by Wilson Pickett
                System.out.println("\n------- asking if it contains \"Its Too Late\" by Wilson Pickett");
                testRecord = new Record("Its Too Late", "Wilson Pickett");
                System.out.println("Does it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

                //ask it what slot "Great Balls of Fire" by Jerry Lee Lewis is in
                System.out.println("\n------- asking what slot \"Great Balls of Fire\" by Jerry Lee Lewis is in");
                testRecord = new Record("Great Balls of Fire", "Jerry Lee Lewis");
                System.out.println("\nWhat slot is " + testRecord + " in?: " + myJukebox.findSlot(testRecord));

                //ask it what slot "The Great Pretender" by The Platters is in
                System.out.println("\n------- asking what slot \"The Great Pretender\" by The Platters is in");
                testRecord = new Record("The Great Pretender", "The Platters");
                System.out.println("What slot is " + testRecord + " in?: " + myJukebox.findSlot(testRecord));

                //tell it to remove "Wooly Booly" by Sam the Sham & the Pharaohs
                System.out.println("\n------- telling it to remove \"Wooly Booly\" by Sam the Sham & the Pharaohs");
                testRecord = new Record("Wooly Bully", "Sam the Sham & the Pharaohs");
                System.out.println("\nDid it successfully remove " + testRecord + "?: " + myJukebox.remove(testRecord));

                //tell it to remove "Heartbreak Hotel" by Elvis Presley
                System.out.println("\n------- telling it to remove \"Heartbreak Hotel\" by Elvis Presley");
                testRecord = new Record("Heartbreak Hotel", "Elvis Presley");
                System.out.println("Did it successfully remove " + testRecord + "?: " + myJukebox.remove(testRecord));

                //print it (using S.O.P)
                System.out.println("\n------- printing the Jukebox (should have 4 Records, without \"Wooly Booly\" by Sam the Sham & the Pharaohs");
                System.out.println("\nJukebox now contains: " + myJukebox);

        }
}

Answer 1

/**
* This class describes a (pre-CD) record
*/
public class Record {
  
   // data
   private String title;
   private String artist;

   /**
   * Default constructor
   * @param theTitle
   * @param theArtist
   */
   public Record(String theTitle, String theArtist) {
       this.title = theTitle;
       this.artist = theArtist;
   }

   /**
   * @return the title
   */
   public String getTitle() {
       return title;
   }

   /**
   * @param title the title to set
   */
   public void setTitle(String title) {
       this.title = title;
   }

   /**
   * @return the artist
   */
   public String getArtist() {
       return artist;
   }

   /**
   * @param artist the artist to set
   */
   public void setArtist(String artist) {
       this.artist = artist;
   }

   @Override
   public boolean equals(Object obj) {
       if(obj != null) {
           if(obj instanceof Record) {
               Record other = (Record) obj;
               if((this.artist.equalsIgnoreCase(other.artist)) &&
                       (this.title.equalsIgnoreCase(other.title)))
                   return true;
           }
       }

       return false;
   }

   @Override
   public String toString() {
       return String.format("%-7s %-20s \t%-7s %s", "Title: ", this.title, "Artist: ", this.artist);
   }
}

public interface JukeInterface {

   /**
   * insert(Record aRecord) - inserts a Record at the last position in
   * thejukebox
   *
   * @param aRecord
   */
   public void insert(Record aRecord);

   /**
   * insert(int slot, Record aRecord) - inserts a Record into a specific slot
   * in the jukebox
   *
   * @param slot
   * @param aRecord
   */
   public void insert(int slot, Record aRecord);

   /**
   * remove(Record aRecord) - removes a Record from the jukebox. If the Record
   * does not exist, it is unchanged.
   *
   * @param aRecord
   * @return
   */
   public boolean remove(Record aRecord);

   /**
   * contains(Record aRecord) - returns true if the jukebox contains the
   * Record
   *
   * @param aRecord
   * @return
   */
   public boolean contains(Record aRecord);

   /**
   * findSlot(Record aRecord) - returns the slot that has the Record (-1 if
   * not there)
   *
   * @param aRecord
   * @return
   */
   public int findSlot(Record aRecord);

   /**
   * random() - returns a Record, chosen at random FOR EXAMPLE, to generate a
   * random int between 0 and 9 (inclusive) 1. create a new instance of Random
   * --> Random gen = new Random(); 2. tell it to return a random int between
   * 0 and 9 (inclusive) --> int theRand = gen.nextInt(10); OR: to generate a
   * random int between 0 and 9 (inclusive), use (int)(Math.random()*10);
   *
   * @return
   */
   public Record random();

   /**
   * toString() - returns this jukebox's representation as a String. Should
   * show the contents.
   *
   * @return
   */
   public String toString();
}

/**
* This class implements the methods of the JukeInterface
* to modify the arraylist recordList
*/
import java.util.ArrayList;
import java.util.Random;

public class Jukebox implements JukeInterface {

   //Attributes
   private ArrayList<Record> recordList;
  
   /**
   * Defautlt constructor
   */
   public Jukebox() {
       this.recordList = new ArrayList<Record>();
   }

   /**
   * insert(Record aRecord) - inserts a Record at the last position in
   * thejukebox
   *
   * @param aRecord
   */
   @Override
   public void insert(Record aRecord) {
       if(aRecord != null)
           this.recordList.add(aRecord);
   }

   /**
   * insert(int slot, Record aRecord) - inserts a Record into a specific slot
   * in the jukebox
   *
   * @param slot
   * @param aRecord
   */
   @Override
   public void insert(int slot, Record aRecord) {
       if(aRecord != null)
           this.recordList.add(slot, aRecord);
   }

   /**
   * remove(Record aRecord) - removes a Record from the jukebox. If the Record
   * does not exist, it is unchanged.
   *
   * @param aRecord
   * @return
   */
   @Override
   public boolean remove(Record aRecord) {
       return this.recordList.remove(aRecord);
   }

   /**
   * contains(Record aRecord) - returns true if the jukebox contains the
   * Record
   *
   * @param aRecord
   * @return
   */
   @Override
   public boolean contains(Record aRecord) {
       return this.recordList.contains(aRecord);
   }

   /**
   * findSlot(Record aRecord) - returns the slot that has the Record (-1 if
   * not there)
   *
   * @param aRecord
   * @return
   */
   @Override
   public int findSlot(Record aRecord) {
       return this.recordList.indexOf(aRecord);
   }

   /**
   * random() - returns a Record, chosen at random FOR EXAMPLE, to generate a
   * random int between 0 and 9 (inclusive)
   * 1. create a new instance of Random
   * --> Random gen = new Random();
   * 2. tell it to return a random int between
   * 0 and 9 (inclusive) --> int theRand = gen.nextInt(10);
   * OR:
   * to generate a
   * random int between 0 and 9 (inclusive), use (int)(Math.random()*10);
   *
   * @return
   */
   @Override
   public Record random() {
       Random r = new Random();
       int size = this.recordList.size();
       return this.recordList.get(r.nextInt(size));
   }

   /**
   * toString() - returns this jukebox's representation as a String. Should
   * show the contents.
   *
   * @return
   */
   @Override
   public String toString() {
       StringBuffer sb = new StringBuffer();
       for (Record record : recordList) {
           sb.append("\n" + record);
       }
      
       return sb.toString();
   }
}

/**
* This class will test the Jukebox and Record classes which were parts of the
* ArrayLists, Vectors minilab
*
* @author Admin
*
*/
public class JukeTester {
   public static void main(String[] args) {
       // testRecord will be used for queries
       Record testRecord;

       System.out.println("------- Creating a new Jukebox and inserting only 1 Record");
       Jukebox myJukebox = new Jukebox();
       myJukebox.insert(new Record("Kokomo", "The Beach Boys"));

       // print it (using S.O.P.)
       System.out.println("\n------- printing the Jukebox (tests Jukebox's and Record's toString())");
       System.out.println("Jukebox now contains: " + myJukebox);

       // tell it to return 5 random records
       System.out.println("\n------- telling it to return 5 random Records (should all be the same)");
       System.out.println("\nA random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());

       System.out.println("\n------- creating a different new Jukebox and telling it to insert 5 Records");
       myJukebox = new Jukebox();
       myJukebox.insert(new Record("Kokomo", "The Beach Boys"));
       myJukebox.insert(new Record("Wooly Bully", "Sam the Sham & the Pharaohs"));
       myJukebox.insert(new Record("Mustang Sally", "Wilson Pickett"));
       myJukebox.insert(1, new Record("Great Balls of Fire", "Jerry Lee Lewis"));
       myJukebox.insert(0, new Record("I Feel Good", "James Brown"));

       // print it (using S.O.P.)
       System.out.println("\n------- printing the Jukebox (tests Jukebox's and Record's toString())");
       System.out.println("Jukebox now contains: " + myJukebox);

       // tell it to return 5 random records
       System.out.println("\n------- telling it to return 5 random Records (the random Records will vary)");
       System.out.println("\nA random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());
       System.out.println("A random Record is: " + myJukebox.random());

       // ask it if it contains "Kokomo" by The Beach Boys
       System.out.println("\n------- asking if it contains \"Komomo\" by the Beach Boys");
       System.out.println("            (tests existance of .equals that receives an Object)");
       testRecord = new Record("Kokomo", "The Beach Boys");
       System.out.println("\nDoes it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

       // ask it if it contains "Kokomo" by The Beach Boys (with different
       // Strings for title/artist)
       System.out.println("\n------- asking if it contains \"Komomo\" by the Beach Boys");
       System.out.println("            (test created with title/artist in different memory locations)");
       System.out.println("            tests whether Records .equals usings String's .equals when comparing title and artist)");
       testRecord = new Record(new String("Kokomo"), new String("The Beach Boys"));
       System.out.println("\nDoes it contain " + testRecord + "?: "+ myJukebox.contains(testRecord));

       // ask it if it contains "Mustang Sally" by the Commitments
       System.out.println("\n------- asking if it contains \"Mustang Sally\" by the Commitments");
       testRecord = new Record("Mustang Sally", "The Commitments");
       System.out.println("Does it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

       // ask it if it contains "Its Too Late" by Wilson Pickett
       System.out.println("\n------- asking if it contains \"Its Too Late\" by Wilson Pickett");
       testRecord = new Record("Its Too Late", "Wilson Pickett");
       System.out.println("Does it contain " + testRecord + "?: " + myJukebox.contains(testRecord));

       // ask it what slot "Great Balls of Fire" by Jerry Lee Lewis is in
       System.out.println("\n------- asking what slot \"Great Balls of Fire\" by Jerry Lee Lewis is in");
       testRecord = new Record("Great Balls of Fire", "Jerry Lee Lewis");
       System.out.println("\nWhat slot is " + testRecord + " in?: " + myJukebox.findSlot(testRecord));

       // ask it what slot "The Great Pretender" by The Platters is in
       System.out.println("\n------- asking what slot \"The Great Pretender\" by The Platters is in");
       testRecord = new Record("The Great Pretender", "The Platters");
       System.out.println("What slot is " + testRecord + " in?: " + myJukebox.findSlot(testRecord));

       // tell it to remove "Wooly Booly" by Sam the Sham & the Pharaohs
       System.out.println("\n------- telling it to remove \"Wooly Bully\" by Sam the Sham & the Pharaohs");
       testRecord = new Record("Wooly Bully", "Sam the Sham & the Pharaohs");
       System.out.println("\nDid it successfully remove " + testRecord + "?: " + myJukebox.remove(testRecord));

       // tell it to remove "Heartbreak Hotel" by Elvis Presley
       System.out.println("\n------- telling it to remove \"Heartbreak Hotel\" by Elvis Presley");
       testRecord = new Record("Heartbreak Hotel", "Elvis Presley");
       System.out.println("Did it successfully remove " + testRecord + "?: " + myJukebox.remove(testRecord));

       // print it (using S.O.P)
       System.out.println("\n------- printing the Jukebox (should have 4 Records, without \"Wooly Booly\" by Sam the Sham & the Pharaohs");
       System.out.println("\nJukebox now contains: " + myJukebox);
   }
}

SAMPLE OUTPUT: