Pass serializable object throught intent

Question

This is my first attempt to ask for a solution to a problem of mine so try to be kind guys! I have found numerous solutions to problems I deal with in this site by doing simple search but this time I had no luck I guess. I found nothing to fit my problem so I ended asking a new question.

I 'm trying to pass an object through an intent from one activity to another. I have one abstract class and two subclasses (the one of them also abstract) as follows. I need them to be abstract. I removed a lot of code (abstract methods etc.) just to find what the problem is and I ended up with these really simple classes and I still have the same problem.

public abstract class MyObject {

    private boolean New;
    private boolean Modified;

    public MyObject() {
        New = true;
    }

    public boolean isNew() {
        return New;
    }

    protected void setNew(boolean value) {
        New = value;
    }

    protected boolean isModified() {
        return Modified;
    }

    protected void setModified(boolean value) {
        Modified = value;
    }

}

public abstract class MyItemBase extends MyObject {

    private Long Id;
    private String Description;

    public MyItemBase() {
        super();
    }

    public Long getId() {
        return Id;
    }

    public void setId(Long id) {
        Id = id;
    }

    public String getDescription() {
        return Description;
    }

    public void setDescription(String description) {
        Description = description;
    }

}

public class MyItem extends MyItemBase implements Serializable {

    private static final long serialVersionUID = -2875901021692711701L;

    public MyItem() {
        super();
    }

}

I have two Activities, ActivityA with a button to call ActivityB as follows.

public class ActivityA extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_a);

        Button btn = (Button) findViewById(R.id.button);
        btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(getApplicationContext(),
                        ActivityB.class);

                MyItem item = new MyItem();
                item.setId((long) 1);
                item.setDescription("test");

                intent.putExtra("MyItem", (Serializable) item);
                startActivityForResult(intent, 1);
            }

        });
    }

}

public class ActivityB extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_b);

        MyItem item = (MyItem) getIntent().getSerializableExtra("MyItem");
        ((TextView) findViewById(R.id.text)).setText(item.getDescription());
    }

}

So when I receive MyItem from the second activity, with no errors at all, both properties Id and Description are null. Actually it's a new object because the New property is true. Now if I try to get the object exactly after I put it in the intent in the first Activity like that

intent.putExtra("MyItem", (Serializable) item);
MyItem newItem = (MyItem) intent.getSerializableExtra("MyItem");
startActivityForResult(intent, 1);

it works fine. newItem has all the properties with the correct values.

Any ideas?

Thanx in advance everybody!

Answer 1

From the official Serializable doc:

Classes that do not implement this interface will not have any of their state serialized or deserialized. All subtypes of a serializable class are themselves serializable.

Your base class doesn't implement Serializable, so its fields are not getting serialized.

Make MyItemBase (or even MyObject) Serializable and all of its descendants will also become Serializable (without explicitly implementing the interface).