Unable to add an element to an arraylist using extended class

[Jon Kho]

Dear all,
I am facing a problem of using an class which is a sub class of another. Using in the sense, putting the attributes of the extended class into the arraylist that initially uses the original class for the main class. I hope to understand more about this problem. Here are the codes..

import java.io.Serializable;

public abstract class Item implements Serializable {
    
    private String compactDisc;                 
    private String title;               
    private boolean hireStatus;                 
    
    /**
     * Constructor
     */
    public CompactDisc(String id, String name)         
    {
        // Assign a unique itemId
        this.itemId = id; 
        this.title = name;
        this.sHire = false;
    }
    

    public String getItemId()
    {
        return this.itemId;
    }
    

    public String getTitle()
    {
        return this.title;
    }
        

    public boolean isHired()
    {
        return onHire;
    }

    }
    
}

public class DVD extends compactDisc{
    
    private String manufacturer; 
    private String year;


    public Game(String id, String name, String madeBy, String yr) 
    {
        super(id, name);
        this.manufacturer = madeBy;
        this.year = yr;
    }
    

    public String getManufacturer()
    {
        return this.manufacturer;
    }


    public String getYear()
    {
        return this.year;
    }
}

any comments or help on this topic will be great.

regards,
Jon

[Henry Wong]

I am facing a problem of using an class which is a sub class of another.

I am assuming that the problem that you are facing, is that it won't compile? As neither of the two classes have constructors that has the same name as the class. (and if they are methods, then they don't have a return type).

Henry

[Jon Kho]

Hi Henry,

Thanks for replying.

Actually I am using the methods like this.

try {
            for (CompactDisc cd : discs) //discs is the array list using the main class attributes but i can't use 
            {
                    out.writeObject(g);

            }
        }

and it shows this when i highlight it.

incompatible types
found CompactDisc
required: DVD


any comments or help on this topic would be great!

thanks

[Jon Kho]

dear all,

does this thread able to help me to solve the current problem? Now I am trying to figure out the function of the "buffer"...

any comments or help on this thread would be great!

edit: This above coding does not work on my coding because the current class has this..
public class DVD extends CompactDisc {

also i found an example from here which i understand but i am unable to implement it on the code which i have..

Regards,
Jon