Network Checking

Determining and Monitoring the Connectivity Status

Some of the most common uses for repeating alarms and background services is to schedule regular updates of application data from Internet resources, cache data, or execute long running downloads. But if you aren’t connected to the Internet, or the connection is too slow to complete your download, why bother waking the device to schedule the update at all?

You can use the ConnectivityManager to check that you’re actually connected to the Internet, and if so, what type of connection is in place.

Determine if You Have an Internet Connection

There’s no need to schedule an update based on an Internet resource if you aren’t connected to the Internet. The following snippet shows how to use the ConnectivityManager to query the active network and determine if it has Internet connectivity.

MainActivity.java

package androiindians.helloworld;
import android.app.Activity;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.widget.Toast;
public class MainActivity extends Activity {
    Boolean isInternetPresent = false;    
    ConnectionDetector cd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        cd = new ConnectionDetector(getApplicationContext());
        isInternetPresent = cd.isConnectingToInternet();
        if (isInternetPresent) {

            Toast.makeText(MainActivity.this,"Internet is there",Toast.LENGTH_LONG).show();
        }
        else{
            showAlertDialog(MainActivity.this, "Internet", "No internet connection...", false);
        }
    }
    private void showAlertDialog(final Context context, String title, String message, Boolean status) {
        AlertDialog alertDialog = new AlertDialog.Builder(context).create();
        alertDialog.setTitle(title);
        alertDialog.setMessage(message);
        alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);
         alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
            }
        });

        alertDialog.show();
    }
   }

ConnectionDetector.Java

package androiindians.helloworld;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class ConnectionDetector { 
    private Context _context; 
    public ConnectionDetector(Context context){
        this._context = context;
    }
    public boolean isConnectingToInternet(){
        ConnectivityManager connectivity = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
          if (connectivity != null)
          {
         NetworkInfo[] info = connectivity.getAllNetworkInfo();
              if (info != null)
                  for (int i = 0; i < info.length; i++)
                      if (info[i].getState() == NetworkInfo.State.CONNECTED)
                      {
                          return true;
                      } 
          }
          return false;
    }
}

Android Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="androiindians.helloworld">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>