BasePresenterActivity.java

package com.pluscubed.plustimer.base;

import android.app.LoaderManager;
import android.content.Loader;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;

public abstract class BasePresenterActivity<P extends Presenter<V>, V> extends AppCompatActivity {

    private static final String TAG = "base-activity";
    private static final int LOADER_ID = 101;
    protected P presenter;

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

        PresenterFactory<P> presenterFactory = getPresenterFactory();

        if(presenterFactory!=null) {
            getLoaderManager().initLoader(LOADER_ID, null, new LoaderManager.LoaderCallbacks<P>() {
                @Override
                public final Loader<P> onCreateLoader(int id, Bundle args) {
                    Log.i(TAG, "onCreateLoader");
                    return new PresenterLoader<>(BasePresenterActivity.this, presenterFactory);
                }

                @Override
                public final void onLoadFinished(Loader<P> loader, P presenter) {
                    Log.i(TAG, "onLoadFinished");
                    BasePresenterActivity.this.presenter = presenter;
                    onPresenterPrepared(presenter);
                }

                @Override
                public final void onLoaderReset(Loader<P> loader) {
                    Log.i(TAG, "onLoaderReset");
                    BasePresenterActivity.this.presenter = null;
                    onPresenterDestroyed();
                }
            });
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        if(presenter!=null)
            presenter.onViewAttached(getPresenterView());
    }

    @Override
    protected void onStop() {
        super.onStop();
    }

    @Override
    protected void onDestroy() {
        if(presenter!=null)
            presenter.onViewDetached();
        super.onDestroy();
    }

    /**
     * Default: returns null, disables MVP loader
     */
    protected PresenterFactory<P> getPresenterFactory(){
        return null;
    }

    protected void onPresenterPrepared(P presenter){

    }

    protected void onPresenterDestroyed() {
        // hook for subclasses
    }

    // Override in case of Activity not implementing Presenter<View> interface
    protected V getPresenterView() {
        return (V) this;
    }
}