import android.content.Intent;
import android.graphics.Rect;
import android.os.Bundle;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnGroupClickListener;
import android.widget.ImageView;
import android.widget.Toast;

public class Two extends AppCompatActivity implements AbsListView.OnScrollListener, NavigationView.OnNavigationItemSelectedListener  {

    private boolean viewIsAtHome;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.two);




        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        displayView(R.id.nav_news);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

         (................)

    }

    (...........)

    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        }
        if (!viewIsAtHome) { //if the current view is not the News fragment
            displayView(R.id.nav_news); //display the News fragment
        } else {
            moveTaskToBack(true);  //If view is in News fragment, exit application
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {

        displayView(item.getItemId());
        return true;
        // Handle navigation view item clicks here.

    }


    public void displayView(int viewId) {

        Fragment fragment = null;
        String title = getString(R.string.app_name);

        switch (viewId) {
            case R.id.nav_news:
                fragment = new First_Fragment();
                title = getString(R.string.firstfragment);
                title  = "News";
                viewIsAtHome = true;

                break;
            case R.id.nav_events:
                fragment = new Second_Fragment();
                title = getString(R.string.secondfragment);
                title = "Events";
                viewIsAtHome = false;
                break;
            case R.id.nav_gallery:
                Intent intent = new Intent(Two.this, MainActivity.class);
                startActivity(intent);
                viewIsAtHome = false;
                break;

        }

        if (fragment != null) {
            FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            ft.replace(R.id.content_frame, fragment);
            ft.commit();
        }

        // set the toolbar title
        if (getSupportActionBar() != null) {
            getSupportActionBar().setTitle(title);
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);

    }


}