AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="your.package.name" >
	
	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
	<uses-permission android:name="android.permission.INTERNET" />
	<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
		android:name="your.package.name.MyApp"
        android:theme="@style/AppTheme" >
		<receiver 
			android:enabled="true"
            android:exported="true"
			android:label="BR"
			android:name="your.package.name.main.NetworkStateReceiver" >
			<intent-filter>
				<action android:name="android.intent.action.BOOT_COMPLETED" > </action>
				<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
			</intent-filter>
		</receiver>
        <activity
            android:name="your.package.name.main.MainActivity"
            android:label="@string/app_name"
			android:theme="@style/AppTheme.BrandedLaunch" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

MainActivity.java

import com.smontiel.strap.support.v7.AppCompatActivity;
import android.os.Bundle;
//import de.greenrobot.event.EventBus;
import android.widget.Toast;
import com.squareup.otto.*;
import android.content.*;
import android.net.*;

public class MainActivity extends AppCompatActivity
{
	private String TAG = MainActivity.class.getSimpleName();
	Bus bus =MyApp.getBus();
	@Override protected void onPreInject()
	{ setContentView(R.layout.main); }

	NetworkStateReceiver mReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
		setTheme(R.style.AppTheme);
        super.onCreate(savedInstanceState);

		bus.post(new NetworkStateChanged(false) );
		//EventBus.getDefault().register(this); 
		// register EventBus
	}

	@Override
	protected void onStart()
	{
		super.onStart();
		//bus.register(this);
	}

	@Override
	protected void onResume()
	{
		this.mReceiver = new NetworkStateReceiver();
		registerReceiver(this.mReceiver, 
				new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
		super.onResume();
		bus.register(this);
	}
	@Override
	protected void onPause()
	{
		unregisterReceiver(mReceiver);
		super.onPause();
		bus.unregister(this);
	}
	
	
	@Override
	protected void onDestroy()
	{ super.onDestroy();
	    //bus.unregister(this);
		//EventBus.getDefault().unregister(this); 
		// unregister EventBus
	} 
	// method that will be called when someone posts an event NetworkStateChanged 
	@Subscribe
	public void onEventMainThread(NetworkStateChanged event)
	{
		if (!event.isInternetConnected())
		{
			Toast.makeText(this, "No Internet connection!", Toast.LENGTH_SHORT).show();
		}else{Toast.makeText(this, " Internet connection!", Toast.LENGTH_SHORT).show();}
	} 
}

MyApp.java

import com.squareup.otto.*;
import android.app.*;

public class MyApp extends Application
{
	private static Bus mEventBus;

    public static Bus getBus() {
        return mEventBus;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        mEventBus = new Bus(ThreadEnforcer.ANY);
    }
}

NetworkStateChanged.java

public class NetworkStateChanged 
{
	public boolean mIsInternetConnected;
	public NetworkStateChanged(boolean isInternetConnected) 
	{ 
		this.mIsInternetConnected = isInternetConnected;
	}
	public boolean isInternetConnected() 
	{
		return this.mIsInternetConnected;
	}
} 

NetworkStateReceiver.java

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.widget.*;
//import de.greenrobot.event.EventBus;

public class NetworkStateReceiver extends BroadcastReceiver
{
	// post event if there is no Internet connection
	public void onReceive(Context context, Intent intent) 
	{
		//super.onReceive(context, intent); 
		if(intent.getExtras()!=null)
		{
			NetworkInfo ni=(NetworkInfo) intent.getExtras().get(ConnectivityManager.EXTRA_NETWORK_INFO); 
			if(ni!=null && ni.getState()==NetworkInfo.State.CONNECTED)
			{
				//Toast.makeText(context, "Si hay",1).show();
				MyApp.getBus().post(new NetworkStateChanged(true) );
				// there is Internet connection
			} else
				MyApp.getBus().post(new NetworkStateChanged(false) );
				if(intent .getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY,Boolean.FALSE)) 
				{ 
					// no Internet connection, send network state changed 
					MyApp.getBus().post(new NetworkStateChanged(false) );
					//EventBus.getDefault().post(new NetworkStateChanged(false));
				} 
		} 
	}
}

Hi, Thanks for your gist.
But in line 28 NetworkStateReceiver.java, why do you call post event again? As i read, the event already post in line 24.

do you think it will consume more power battery of mobile?

All you need is a receiver declaration and intent filter. Why would you subject yourself to the rest of the spaghetti?

how to use in Fragment?

How do you stop it when the Activity changes?

Using canary it shows this as a memory leak.

android.net.conn.CONNECTIVITY_CHANGE
This is deprecated for Android N and higher