Simple MVP Example

MainActivity.java

package butzow.me.chan.ui.main;

import android.support.design.widget.Snackbar;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;

import com.mikepenz.materialize.MaterializeBuilder;

import java.util.List;

import butterknife.Bind;
import butterknife.ButterKnife;
import butzow.me.chan.R;
import butzow.me.chan.retrofit.Boards;
import timber.log.Timber;

public class MainActivity extends AppCompatActivity implements IMainView, SwipeRefreshLayout.OnRefreshListener, MainRecyclerAdapter.Callback {
    @Bind(R.id.recyclerView)
    RecyclerView recyclerView;

    @Bind(R.id.toolbar)
    Toolbar toolbar;

    private IMainPresenter presenter;
    private MainRecyclerAdapter recyclerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        setSupportActionBar(toolbar);
        new MaterializeBuilder(this).build();

        recyclerAdapter = new MainRecyclerAdapter(this, this);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setHasFixedSize(true);
        recyclerView.setAdapter(recyclerAdapter);

        presenter = new MainPresenter(this);
        presenter.loadBoards();
    }

    @Override
    public void displayBoards(List<Boards.Board> boards) {
        Timber.i("displayBoards()");
        recyclerAdapter.updateBoards(boards);
    }

    @Override
    public void displayBoardError(Throwable t, int stringRes) {
        Timber.i("displayBoardError");

        Timber.e(t.toString());
        Snackbar.make(findViewById(R.id.coordinatorLayout), stringRes, Snackbar.LENGTH_LONG)
        .setAction(R.string.action_retry, v -> {
            presenter.loadBoards();
        }).show();
    }

    @Override
    public void onRefresh() {
        presenter.loadBoards();
    }

    @Override
    public void onItemClicked(String board, String title) {
        startActivity(presenter.getBoardIntent(this, board, title));
    }
}

MainPresenter.java

package butzow.me.chan.ui.main;

import android.content.Context;
import android.content.Intent;

import butzow.me.chan.R;
import butzow.me.chan.retrofit.Boards;
import butzow.me.chan.ui.board.BoardActivity;
import retrofit.Callback;
import retrofit.Response;
import retrofit.Retrofit;
import timber.log.Timber;

/**
 * @author cr5315
 */
public class MainPresenter implements IMainPresenter {
    private IMainView view;

    public MainPresenter(IMainView view) {
        this.view = view;
    }

    @Override
    public void loadBoards() {
        Timber.i("loadBoards()");

        Boards.getAdapter().getBoards().enqueue(new Callback<Boards.Boardz>() {
            @Override
            public void onResponse(Response<Boards.Boardz> response, Retrofit retrofit) {
                view.displayBoards(response.body().getBoards());
            }

            @Override
            public void onFailure(Throwable t) {
                view.displayBoardError(t, R.string.activity_main_error_loading_boards);
            }
        });
    }

    @Override
    public Intent getBoardIntent(Context context, String board, String title) {
        Intent intent = new Intent(context, BoardActivity.class);
        intent.putExtra(BoardActivity.EXTRA_BOARD, board);
        intent.putExtra(BoardActivity.EXTRA_TITLE, title);
        return intent;
    }
}