Latihan Inheritance (Pewarisan)

Dalam latihan ini, study casenya adalah membuat class untuk menyimpan CD dan DVD dalam Class yang berbeda. Karena adanya properti yang sama dan berbeda di masing-masing item, maka dibuat suatu class "orangtua" (Item).

Kode :
1. Item.java
 
public class item
{
   
    private String title;
    private int playingTime;
    private boolean gotlt;
    private String comment;
    public item(String theTitle, int time)
    {
        title = theTitle;
        playingTime = time;
        gotlt = false;
        comment = "";
    }
    public void setComment(String comment)
    {
        this.comment=comment;
    }
    public String getComment()
    {
        return comment;
    }
    public void setOwn(boolean ownlt)
    {
        gotlt=ownlt;
    }
    public boolean getOwn()
    {
        return gotlt;
    }
    public void print()
    {
        System.out.print("title:"+title+"(" + playingTime + "mins)");
        if(gotlt)
        {
            System.out.println("*");
        }
        else
        {
            System.out.println(" " + comment);
        }
    }
}

2. CD.java

/**
 * kelas fungsi cd yang tidak ada di item
 */
public class cd extends item
{
    private String artist;
    private int numberOfTracks;

    public cd(String theTitle, String theArtist, int tracks, int time)
    {
        super(theTitle,time);
        artist = theArtist;
        numberOfTracks = tracks;
    }
    public String getArtist()
    {
        return artist;
    }
    public int getNumberOfTracks()
    {
        return numberOfTracks;
    }
}

3. DVD.java

/**
 * kelas fungsi dvd yang tidak ada di item
 * @version 1.0.1
 */
public class dvd extends item
{
    private String director;
    public dvd(String theTitle, String theDirector, int time)
    {
        super(theTitle,time);
        director=theDirector;
    }
    public String getDirector()
    {
        return director;
    }
   
}

4. Database.java

/**
 * @author abdi teh Alberto
 */
import java.util.ArrayList;
public class Database
{
    // instance variables - replace the example below with your own
    private ArrayList<item>items ;
    public Database()
    {
        items=new ArrayList<item>();
    }
    public void additem(item theItem)
    {
        items.add(theItem);
    }
    public void list()
    {
        for(item item:items)
        {
            item.print();
            System.out.println();
        }
    }
}