ExampleActivity.java

package com.example.activity;

import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Gravity;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;

import com.example.R;
import com.example.fragment.ExampleFragment;

public class ExampleActivity extends AppCompatActivity {
	private DrawerLayout mDrawerLayout;
	private NavigationView mNavigationView;
	private ActionBarDrawerToggle mDrawerToggle;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_example);
		setupActionBar();
		setupDrawer(savedInstanceState);
		setupHeader();
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// open or close the drawer if home button is pressed
		if (mDrawerToggle.onOptionsItemSelected(item)) {
			return true;
		}

		// action bar menu behavior
		switch (item.getItemId()) {
			case android.R.id.home:
				// TODO
				return true;

			default:
				return super.onOptionsItemSelected(item);
		}
	}

	@Override
	protected void onPostCreate(Bundle savedInstanceState) {
		super.onPostCreate(savedInstanceState);
		mDrawerToggle.syncState();
	}

	@Override
	public void onConfigurationChanged(Configuration newConfiguration) {
		super.onConfigurationChanged(newConfiguration);
		mDrawerToggle.onConfigurationChanged(newConfiguration);
	}

	@Override
	public void onBackPressed() {
		if (mDrawerLayout.isDrawerOpen(Gravity.LEFT)) {
			mDrawerLayout.closeDrawer(Gravity.LEFT);
		} else {
			super.onBackPressed();
		}
	}

	private void setupActionBar() {
		Toolbar toolbar = findViewById(R.id.toolbar);
		setSupportActionBar(toolbar);

		ActionBar bar = getSupportActionBar();
		bar.setDisplayUseLogoEnabled(false);
		bar.setDisplayShowTitleEnabled(true);
		bar.setDisplayShowHomeEnabled(true);
		bar.setDisplayHomeAsUpEnabled(true);
		bar.setHomeButtonEnabled(true);
	}

	private void setupDrawer(Bundle savedInstanceState) {
		// reference
		mDrawerLayout = findViewById(R.id.example_drawer_layout);
		mNavigationView = findViewById(R.id.example_drawer_navigation);

		// navigation
		mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
			@Override
			public boolean onNavigationItemSelected(@NonNull MenuItem item) {
				selectDrawerItem(item);
				return true;
			}
		});

		// toggle
		mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, R.string.drawer_open, R.string.drawer_close) {
			@Override
			public void onDrawerClosed(View view) {
				supportInvalidateOptionsMenu();
			}

			@Override
			public void onDrawerOpened(View drawerView) {
				supportInvalidateOptionsMenu();
			}
		};
		mDrawerLayout.addDrawerListener(mDrawerToggle);

		// show initial fragment
		if (savedInstanceState == null) {
			MenuItem item = mNavigationView.getMenu().findItem(R.id.menu_navigation_example1);
			selectDrawerItem(item);
		}
	}

	private void setupHeader() {
		// reference
		TextView titleTextView = mNavigationView.getHeaderView(0).findViewById(R.id.navigation_header_title);

		// title
		titleTextView.setText("Hello world");
	}

	private void selectDrawerItem(MenuItem item) {
		Fragment fragment = null;
		Intent intent = null;

		switch (item.getItemId()) {
			case R.id.menu_navigation_example1:
			case R.id.menu_navigation_example2:
			case R.id.menu_navigation_example3:
				fragment = ExampleFragment.newInstance();
				break;

			case R.id.menu_navigation_example4:
			case R.id.menu_navigation_example5:
			case R.id.menu_navigation_example6:
			case R.id.menu_navigation_example7:
				intent = ExampleActivity.newIntent(this);
				break;
		}

		if (fragment != null) {
			FragmentManager fragmentManager = getSupportFragmentManager();
			fragmentManager.beginTransaction().replace(R.id.container_drawer_content, fragment).commitAllowingStateLoss();

			item.setChecked(true);
			getSupportActionBar().setTitle(item.getTitle());
		}

		if (intent != null) {
			startActivity(intent);
		}

		mDrawerLayout.closeDrawers();
	}
}