stankocken/presentation

An architecture for Android as a replacement of MVC.

Presentation

An architecture for Android as a replacement of MVC.

Why should I use Presentation?

Because you want to have more readable, testable code.

Avoid "God Objects", mainly your Activities or Fragments.

How does it work?

Separation of responsibilities by module:

• Presenter: Get a Business Object from the DataProvider and give instructions to the ViewProxy
• DataProvider: Communicate with the "outside" to set and get the data, following the instructions of the Presenter
• ViewProxy: Convert Presenter instructions and set values to Android Views.

Architecture

Leak safe. Don't hold a strong reference to the DataProvider, Presenter, or ViewProxy.

Sample

The goal is to make this application:

Each public method of the modules are defined into an interface:

public interface FormDef {

    interface IPresenter extends Base.IPresenter {

        void onClickSaveButton(String value);
    }

    interface IDataProvider extends Base.IDataProvider {

        String getValueSaved();

        void saveValue(String value);
    }

    interface IView extends Base.IView {

        void setValueSaved(String text);
    }

}

Then you have your:

• FormPresenter that extends BasePresenter and implements FormDef.IPresenter
• FormDataProvider that extends BaseDataProvider and implements FormDef.IDataProvider
• FormViewProxy that extends BaseViewProxy and implements FormDef.IView

The easiest way to use this architecture is to override BaseActivity, even if it's NOT mandatory.

public class FormActivity extends BaseActivity<FormPresenter, FormViewProxy> {

    @Override
    public int getContentView() {
        return R.layout.activity_form;
    }

    @Override
    public Class<FormPresenter> getPresenterClass() {
        return FormPresenter.class; // the class of your presenter to be used within this activity
    }

    @Override
    public FormViewProxy newViewProxy(FormPresenter presenter, Bundle savedInstanceState) {
        return new FormViewProxy(this); // the view proxy, with the Activity in param
    }
}

Note: it also exists a BaseFragment to do exactly the same but within a Fragment.

Go further

Re-use Presenter after Activity destruction

Because BasePresenter extends ViewModel (from Android Architecture), it is possible to re-use the same Presenter after a rotation for example.

When you are using BaseActivity, your presenters will be automatically re-used.

Note: in this case, the DataProvider will also be kept, but you will have to re-create the ViewProxy.

Presenter into an Adapter

This library has a dependency on Efficient Adapter to use the same view cache mechanism.

This allows to apply the Presentation pattern to object in an Adapter as well. Your ViewHolder should extend PresenterViewHolder and your Presenter should extend BaseItemPresenter.

Proguard

Nothing special needed.

Gradle

dependencies {
    compile 'com.skocken:presentation:2.5.0'
}

Android Support library

If you are still using the deprecated Android Support Library (instead of AndroidX), please use the dependency 2.4.X instead.

License

• Apache 2.0

Contributing

Please fork this repository and contribute back using pull requests.

Any contributions, large or small, major features, bug fixes, unit/integration tests are welcomed and appreciated but will be thoroughly reviewed and discussed.

presentation's Issues

Presenter not calling activity lifecycle methods

In my presenter, I don't receive call on onResume, onPause…

This is due to the getActivity() of BasePresenter which is not working for ContextWrapper context.

The fix is to replace getActivity() from BasePresenter to:

public Activity getActivity() {
    Context context = getContext();
    if (context instanceof ContextWrapper) {
        context = ((ContextWrapper) context).getBaseContext();
    }
    if (context instanceof Activity) {
        return (Activity) context;
    } else {
        return null;
    }
}

OnDestroy on a presenter should unsubscribe from ActivityLifeCycle

If I use this lib on an Activity that switch presenter, (e.g an Activity with drawerLayout) I can't unsubscribe from ActivityLifeCycle.

If I use this code

    private void goToMenu(int id) {
        mActualMenuId = id;
        replaceView();
        replacePresenter(newPresenter());
    }

    private void replacePresenter(BasePresenter presenter) {
        BasePresenter actualPresenter = getPresenter();
        if (actualPresenter != null) {
            actualPresenter.onPause();
            actualPresenter.onStop();
            actualPresenter.onDestroy();
        }
        setPresenter(presenter);
        if (presenter != null) {
            presenter.onCreate(null);
            presenter.onStart();
            presenter.onResume();
        }
    }

    private void replaceView() {
        if (mDrawerLayout.getChildCount() == 2) {
            mDrawerLayout.removeViewAt(0);
        }
        int viewId = getViewId();
        if (viewId != 0) {
            View view = LayoutInflater.from(this).inflate(viewId, mDrawerLayout, false);
            mDrawerLayout.addView(view, 0);
        }
    }

And then start a new Activity, when I close the new activity all presenter already shown will be onResumed. Even if it's not present on the screen and if it's view is remove from layout.

One solution to achieve that is to add a method isDestroyed in com.skocken.presentation.util.ActivityLifeCycleListener and a mDestroyed member in BaseProvider class

com.skocken.presentation.util.ActivityLifecycleCallbackDelegate will become:

    @Override
    public void onActivityResumed(Activity activity) {
        if (!isForMe(activity) || mListener == null) {
            return;
        }
        ActivityLifeCycleListener listener = mListener.get();
        if (listener != null && !listener.isDestroyed()) {
            listener.onResume();
        }
    }

And so on...

Can I merge the activity and the viewProxy?

Its an amazing architecture but it make one class to five, I see the activity do nothing, Can I merge the activity and the viewProxy?

README link broken

https://github.com/EfficientAdapter/ yields 404