创建ArrayAdapter的自定义Abstract类

Question

I'd like to create my own abstract version of ArrayAdapter which adds functionality of custom Intent Navigation and Toast popups among others.

Here is an example of my custom Activity:

public abstract class RBActivity extends Activity implements IActivity {

    private Navigator navigator;
    private Toaster toaster;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        navigator = new Navigator(this);
        toaster = new Toaster(this);
    }

    public Navigator navigate() {
        return navigator;
    }

    protected void popBurntToast(String msg) {
        toaster.popBurntToast(msg);
    }

    protected void popToast(String msg) {
        toaster.popToast(msg);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        navigator = null;
        toaster = null;
    }   
}

Then within my Activity's i simply extend from RBActivity instead of Activity . I then can call this.navigate().toSomeActivity(); using my Navigator class which has methods for easily creating intents to navigate around my application. I also have my own RBListActivity etc

Here is a sample method from my navigator class:

public void toSiteSubscribeActivity(Site _site) {
    Intent intent = new Intent(activity, SiteSubscribeActivity.class);
    Bundle b = new Bundle();
    b.putLong(Navigator.INTENT_KEY_CHANNEL_ID, _site.getIdSite());
    b.putString(Navigator.INTENT_KEY_CHANNEL_NAME, _site.getName());
    b.putString(Navigator.INTENT_KEY_CHANNEL_DESCRIPTION, _site.getDescription());
    intent.putExtras(b);
    activity.startActivity(intent);
}    

Anyway, I want to also have a RBArrayAdapter<> but I'm not sure how to create a generic version which doesn't require i specify the class type within the <> braces ie,

public abstract class RBArrayAdapter extends ArrayAdapter<Article> {
    private Navigator navigator;
    private Toaster toaster;

    public RBArrayAdapter(Activity _activity, int _layout, ArrayList<Article> _notes) {
        super(_activity, _layout, _notes);

        navigator = new Navigator(_activity);
        toaster = new Toaster(_activity);
    }


    public Navigator navigate() {
        return navigator;
    }   
}

I tried doing something like public abstract class RBArrayAdapter extends ArrayAdapter<?> but it obviously doesn't work...

I guess in short, I'm asking how to accept a generic class type within the pointy braces

Any help is really appreciated, Cheers

EDIT: ok after looking at ArrayAdapter.java ( https://github.com/android/platform_frameworks_base/blob/master/core/java/android/widget/ArrayAdapter.java ) I think what i need is ArrayAdapter<T> Syntax. looking into that now

Answer 1

If I understand you correctly, you just need the syntax to make this work. Try this:

public abstract class RBArrayAdapter<T> extends ArrayAdapter<T> {
    private Navigator navigator;
    private Toaster toaster;

    public RBArrayAdapter(Activity _activity, int _layout, ArrayList<T> _notes) {
        super(_activity, _layout, _notes);

        navigator = new Navigator(_activity);
        toaster = new Toaster(_activity);
    }


    public Navigator navigate() {
        return navigator;
    }   
}

Then you should be able to substitute any parameter you like for <T> when you instantiate your RBArrayAdapter subclass (something like this):

public class MyStringArrayAdapter extends RBArrayAdapter<String> {

    public MyStringArrayAdapter(Activity _activity, int _layout, ArrayList<String> _notes) {
      super(_activity, _layout, _notes);
    }

}

Have fun.