How to check the internet connection continuously while app is running

Issue

I have created code which checks the internet connection at the start but I want it to keep checking for internet connection in the background and notify the user when connection is lost. I'm new to android so can you please write proper code and help me. This code works fine, I just want it so that it runs in the background to keep a check on internet.

public class isNetworkAvailable extends Activity  {
    @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_is_network);
       ;
            if(!isNetworkAvailable()){
                //Create an alert dialog
                AlertDialog.Builder Checkbuilder = new  AlertDialog.Builder(isNetworkAvailable.this);
                Checkbuilder.setIcon(R.drawable.error);
                Checkbuilder.setTitle("Error!");
                Checkbuilder.setMessage("Check Your Internet Connection.");
                //Builder Retry Button

                Checkbuilder.setPositiveButton("Retry", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int id) {
                        //Restart The Activity
                        Intent intent = getIntent();
                        finish();
                        startActivity(intent);

                    }
                });

                Checkbuilder.setNegativeButton("Exit", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();
                    }
                }) ;

                AlertDialog alert=Checkbuilder.create();
                alert.show();

            }



            else {
                if (isNetworkAvailable()){

                    Thread tr=new Thread(){
                        public  void  run(){
                            try {
                                sleep(4);
                            }
                            catch (Exception e){
                                e.printStackTrace();
                            }
                            finally {
                                Intent i = new Intent(isNetworkAvailable.this,MainActivity.class);
                                startActivity(i);

                                finish();
                            }}};tr.start();}}}private boolean isNetworkAvailable(){
            ConnectivityManager connectivityManager=(ConnectivityManager)this.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeNetworkInfo=connectivityManager.getActiveNetworkInfo();
            return activeNetworkInfo !=null;

        }
    }

Solution

java file this will check for internet when app is start running

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;

public class isNetworkAvailable extends Activity {
    private ImageButton btn;
private Handler h = new Handler();
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_is_network);
            btn = (ImageButton) findViewById(R.id.bu);
   btn.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
                     restar();
       }
   });
                    if (!isNetworkAvailable()) {
                        //Create an alert dialog


                        AlertDialog.Builder Checkbuilder = new AlertDialog.Builder(isNetworkAvailable.this);
                        Checkbuilder.setIcon(R.drawable.error);
                        Checkbuilder.setTitle("Error!");
                        Checkbuilder.setMessage("Check Your Internet Connection.");
                        //Builder Retry Button

                        Checkbuilder.setPositiveButton("Retry", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int id) {
                                //Restart The Activity
                                Intent intent = getIntent();
                                finish();
                                startActivity(intent);

                            }
                        });


                Checkbuilder.setNegativeButton("Exit", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();
                    }
                });

                AlertDialog alert = Checkbuilder.create();
                alert.show();

            } else {
                if (isNetworkAvailable()) {

                    Thread tr = new Thread() {
                        public void run() {
                            try {
                                sleep(4);
                            } catch (Exception e) {
                                e.printStackTrace();
                            } finally {
                                Intent i = new Intent(isNetworkAvailable.this, MainActivity.class);
                                startActivity(i);

                                finish();
                            }
                        }
                    };
                    tr.start();

                }
            }

        }


        private boolean isNetworkAvailable() {
            ConnectivityManager connectivityManager = (ConnectivityManager) this.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
            return activeNetworkInfo != null;

        }

public  void restar(){

            Intent intenet =new Intent(this,isNetworkAvailable.class);

                    startActivity(intenet);
                    finish();
        }
    }

layout file for above java code

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    tools:context=".isNetworkAvailable">


    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="389dp"
        android:layout_height="439dp"
        android:contentDescription="no internet check your connection"
        android:src="@raw/no"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.4"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageButton
        android:id="@+id/bu"
        android:layout_width="335dp"
        android:layout_height="80dp"
        android:layout_below="@id/imageView2"
        android:layout_marginTop="32dp"
        android:contentDescription="Tap to retry"

        android:src="@raw/r"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView2" />
</android.support.constraint.ConstraintLayout>

and just add this line of code will check internet connection continuously

 mWebView.setWebViewClient(new WebViewClient() {
            public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {

                mWebView.loadUrl("file:///android_asset/error.html");

and your android mainfest should be like this

<application
        android:icon="@mipmap/ic_app"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_app_round"
        android:supportsRtl="true"
        android:configChanges="keyboardHidden|orientation|screenSize"
        android:theme="@style/Theme.AppCompat.NoActionBar">
        <activity
            android:name=".isNetworkAvailable"
            android:label="@string/app_name"
            android:theme="@style/Theme.AppCompat.Light.NoActionBar.FullScreen">


            <intent-filter>
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
                <action android:name="android.intent.action.MAIN" />
            </intent-filter>

        </activity>

place this file under assets with name error.html

<!doctype html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="mobile-web-app-capable" content="yes">
    <title>No Connection</title>

    <!-- Stylesheets-->
    <style type="text/css">
 body{
  background: #E1e1e1;
}

#cloud{
  width: 300px;
  height: 120px;
  background: #676767;

  background: -webkit-linear-gradient(-90deg,#676767 5%, #676767 100%);

  -webkit-border-radius: 100px;
  -moz-border-radius: 100px;
  border-radius: 100px;

  position: relative;

  margin: 150px auto 0;
  opacity: .5;
}

#cloud:before, #cloud:after{
  content: '';
  position:absolute;
  background: #676767;
  z-index: -1;
}

#cloud:after{
  width: 100px;
  height: 100px;
  top: -50px;
  left:50px;

  -webkit-border-radius: 100px;
  -moz-border-radius: 100px;
  border-radius: 100px;
}

#cloud:before{
  width: 120px;
  height: 120px;
  top: -70px;
  right: 50px;

  -webkit-border-radius: 200px;
  -moz-border-radius: 200px;
  border-radius: 200px;
}

.shadow {
  width: 300px;
  position: absolute;
  bottom: -10px;
  background: black;
  z-index: -1;

  -webkit-box-shadow: 0 0 25px 8px rgba(0,0,0,0.4);
  -moz-box-shadow: 0 0 25px 8px rgba(0,0,0,0.4);
  box-shadow: 0 0 25px 8px rgba(0,0,0,0.4);

  -webkit-border-radius: 50%;
  -moz-border-radius: 50%;
  border-radius: 50%;

}
h1{
  color: #fff;
  font-size: 25px;
  padding-top: 1px;
  text-align: center ;
  margin: 2px auto;
}

h2 {
  color: #fff;
  font-size: 17px;
  padding-top: 15px;
  text-align: center;
  margin: 5px auto;
}

h4 {
  color: #fff;
  font-size: 14px;
  margin: 0 auto;
  padding: 0;
  text-align: center;
}

 </style>

<body>
<div id="cloud"><h1>Whoops!</h1>
    <h2>Slow or No internet Connection :(</h2>
    <h4>Please Check your WiFi or Mobile Internet!</h4>
    <span class="shadow"></span></div>

</body>
</html>

you need to input all the above code to make it work fine . hope this will help you

Answered By - anshul raj