package com.nilhcem.droidcontn.ui;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.LayoutRes;
import android.support.annotation.Nullable;
import android.support.v4.app.NavUtils;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;

import butterknife.ButterKnife;

public abstract class BaseActivity<P extends BaseActivityPresenter> extends AppCompatActivity {

    protected P presenter;

    protected abstract P newPresenter();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        presenter = newPresenter();
    }

    @Override
    protected void onPostCreate(@Nullable Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        presenter.onPostCreate(savedInstanceState);
    }

    @Override
    protected void onResume() {
        super.onResume();
        presenter.onResume();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        presenter.onSaveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        presenter.onRestoreInstanceState(savedInstanceState);
    }

    @Override
    public void setContentView(@LayoutRes int layoutResID) {
        super.setContentView(layoutResID);
        ButterKnife.bind(this);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                Intent upIntent = NavUtils.getParentActivityIntent(this);
                if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
                    NavUtils.navigateUpFromSameTask(this);
                } else {
                    onBackPressed();
                }
                NavUtils.navigateUpFromSameTask(this);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onBackPressed() {
        if (presenter.onBackPressed()) {
            return;
        }
        super.onBackPressed();
    }

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

package com.nilhcem.droidcontn.ui;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.LayoutRes;
import android.support.annotation.Nullable;
import android.support.v4.app.NavUtils;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;

import butterknife.ButterKnife;

public abstract class BaseActivity<P extends BaseActivityPresenter> extends AppCompatActivity {

    protected P presenter;

    protected abstract P newPresenter();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        presenter = newPresenter();
    }

    @Override
    protected void onPostCreate(@Nullable Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        presenter.onPostCreate(savedInstanceState);
    }

    @Override
    protected void onResume() {
        super.onResume();
        presenter.onResume();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        presenter.onSaveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        presenter.onRestoreInstanceState(savedInstanceState);
    }

    @Override
    public void setContentView(@LayoutRes int layoutResID) {
        super.setContentView(layoutResID);
        ButterKnife.bind(this);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            Intent upIntent = NavUtils.getParentActivityIntent(this);
            if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
                NavUtils.navigateUpFromSameTask(this);
            } else {
                onBackPressed();
            }
            NavUtils.navigateUpFromSameTask(this);
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onBackPressed() {
        if (presenter.onBackPressed()) {
            return;
        }
        super.onBackPressed();
    }

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

Replace switch statement by 'if' statement to increase readability