onBackPressed() Internet no longer detected

Question

I have an application that detects if internet is available or not. I have changed the behaviour of the back button to avoid closing the application when pressed. The issue I'm facing is that when I have 4G or WIFI running and I run the app, it detects that internet is available, however, when I press the back button, the app is put on the background and internet is no longer detected by it.

I noticed that if I remove the permissions in the manifest file, the application works fine, it detects internet both when it is running and when put on background, but I need those permissions for making http post requests later.

Any help on this please?

Thanks.

MainActivity.java

public class MainActivity extends AppCompatActivity {
    Timer timer;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        init();
    }

    @Override
    public void onBackPressed() {
        this.moveTaskToBack(true);
    }

    private void init() {
        timer = new Timer();
        Tasker task = new Tasker(MainActivity.this, timer);
        task.execute();
    }

}

Tasker .java

public class Tasker extends AsyncTask<Void,Void,String> {
    final Handler handler = new Handler();
    static Timer timer;
    Context context;
    Toast toast;
    private TimerTask doAsynchronousTask;

    public Tasker(MainActivity context, Timer timer) {
        this.timer = timer;
        this.context = context;
    }

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected String doInBackground(Void... voids) {
        doTimerTask();
        return null;
    }

    @Override
    protected void onPostExecute(String response) {

    }

    private void showToast(String message){
        toast = Toast.makeText(context, message, Toast.LENGTH_LONG);
        toast.setGravity(Gravity.CENTER, 0, 0);
        if(!((Activity) context).isFinishing()){
            toast.show();
        }
    }

    private void doTimerTask() {
        doAsynchronousTask = new TimerTask() {
            @Override
            public void run() {
                handler.post(new Runnable() {
                    @SuppressWarnings("unchecked")
                    public void run() {
                        if(haveNetworkConnection()){
                            showToast("Online");
                        }else{
                            showToast("Offline");
                        }

                    }
                });
            }
        };
        timer.schedule(doAsynchronousTask, 0,  10000);
    }

    private boolean haveNetworkConnection() {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        boolean isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
        return isConnected;
    }
}

AndroidManifest.xml

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

Answer 1

Actually, it may not be your desirable answer, but I think there is a way simpler way to do what you really want to do using a Broadcast receiver. you don't need to check network state using the timer. here's the link

Answer 2

I would suggest you to use a WorkManager or AlarmManager, or even Services for background related periodic tasks.

Using the Timer-AsyncTask combination is not a feasible approach and it could lead to many problems, one of which being it could easily be terminated by Android once it's in background.

My top pick would be WorkManager as it handles the condition for the tasks for you nicely, for example, if you want to only launch your task if there's internet connection, then you simply add a Work Constraint to your work request like this

Constraint networkConstraint = new Constraints.Builder()
    .setRequiredNetworkType(NetworkType.CONNECTED)
    .build();

workRequest.setConstraints(constraints)

And your task will only be executed if the network is connected. BTW, they don't need to be manually re-set after reboot like AlarmManagers does.

However, there are downsides to it, one of them being the perodic requests can only occur every 15 minutes, which you can circumvent (though not recommended) by setting more one time work requests in each perodic request with smaller intervals of delayed start time.

Anyways, stop using the AsyncTask approach you are using now, and use one of the "legitimate" approaches Android approves to do background tasks, I recommend WorkManager, but based on your situation, you can choose whatever approach you like as long as it's meant to work in background.