Song.java

/*
 * Song class defines a song.
 *
 * @author CS111 - Rutgers University
 */
public class Song {

  private String name;         // Song's name
  private String writers[];     // An array of writer's names, max is 50
  private int numberOfWriters; // Number of writers for this song
  private int year;            // Release year
  private int rating;          // Range [1-5]: 1 (didn't like it), 5 (love it)

  /*
   * Constructor initializes the new Song object
   * @param name is the movie's name
   */
  public Song ( String name ) {
    setName ( name );
    writers = new String[50];
    numberOfWriters = 0;
    year = 0;
    rating = 0;
  }

  /*
   * Updates the song's name
   * @param name is the new name
   */
  public void setName ( String name ) {
    this.name = name;
  }

  /*
   * Returns the movie name
   * @return String the name of the movie
   */
  public String getName () {
    return name;
  }

  /*
   * Updates the movie's year
   * @param year is the year of the movie's release
   */
  public void setYear ( int year ) {
    this.year = year;
  }

  /*
   * Return the movie's release year
   * @return int This is the movie's release year
   */
  public int getYear () {
    return year;
  }

  /*
   * Update the movie's rating
   * @param rating This is the movie's rating
   */
  public void setRating (int rating) {
    this.rating = rating;
  }

  /*
   * Returns the movie's rating
   * @returns int This is the movie's rating
   */
  public int getRating () {
    return rating;
  }

  /*
   * Adds an writer to the Song
   * @param writerName is the writer being added
   */
  public void addWriter (String writerName) {
    if ( numberOfWriters < 50 ) {
      writers[numberOfWriters] = writerName;
      numberOfWriters += 1;
    } else {
      System.out.println("Array of writers is full (max is 50 writers)");
    }
  }

  /*
   * Returns the song's writers list
   * @returns String[] This is the song's writer list
   */
  public String[] getWriters () {
    return writers;
  }

  /*
   * @returns int This song's number of writers
   */
  public int getNumberOfWriters () {
    return numberOfWriters;
  }

  /*
   * Returns the writer name at @index on the song's writers list
   * @param index This is the index in the writer's array
   * @return String The writer's name
   */
  public String getWriterAtIndex (int index) {
    if ( index > numberOfWriters ) {
      System.out.println("Error: no writer at index " + index);
      return null;
    } else {
      return writers[index];
    }
  }

  public boolean equals (Object other) {

    if ( other == null || !(other instanceof Song) ) {
      return false;
    }

    Song otherSong = (Song)other;

    if ( numberOfWriters != otherSong.getNumberOfWriters() ||
	 !otherSong.getName().equals(name) ||
	 otherSong.getYear() != year ) {
      return false;
    }

    // check if all writers of this object are on otherSong
    for ( int i = 0; i < numberOfWriters; i++ ) {
        for ( int k = 0; k < otherSong.getNumberOfWriters(); k++ ) {
          if ( writers[i].equals(otherSong.getWriterAtIndex(k)) ) {
            break;
          } else if ( k == otherSong.getNumberOfWriters()-1 ) {
            // writers[i] not in otherSong, already looked at all items in otherSong
            return false;
          }
      }
    }

    return true;
  }

  /*
   * Compares this Song name against @other lexicographically.
   * @return int positive number if s1 > s2, negative number if s1 < s2, zero if s1 == s2
   */
   public int compareTo (Song other) {
     return this.name.compareTo(other.getName());
   }

  /*
   * toString
   */
  public String toString () {
    String result = name + ", " + year + ", " + rating;
    result += ", [";
    for ( int i = 0; i < numberOfWriters; i++ ) {
      result += writers[i];
      if ( i < numberOfWriters-1 ) {
        result += ", ";
      }
    }
    result += "]";
    return result;
  }
}