Problems with Context in BroadcastReceiver: "Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase openOrCreateDatabase"

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Problems with Context in BroadcastReceiver: "Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase openOrCreateDatabase"

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I have a problem I think with the context when trying to run a BroadcastReceiver, what I try is to connect to an internal sqlite database and read the data. This through an Alarm that runs repeatedly every x minutes.

The code works in MainActivity () but I put the same code in a doInBackground, inside a Receiver and it throws me context error, I already tried different ways but I have not managed to make it work.

I clarify that I am a newbie in Android and if there is something that I never fully understand, it is the context. I leave the code so you can help me.

MainActivity

int interval = 1000*60*2;
Intent intent = new Intent(getApplicationContext(), CheckReclamosReceiver.class);
  pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 234324243, intent, 0);
alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
alarmManager.setRepeating(AlarmManager.RTC, System.currentTimeMillis(), interval, pendingIntent);
Toast.makeText(MainActivity.this, "Alarm set in " + 10 + " seconds", Toast.LENGTH_LONG).show();

CheckReclaimsReceiver

public class CheckReclamosReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        new MyNotificationTask(context).execute();
    }
}

class MyNotificationTask extends AsyncTask<String, String, Void>
{

    public MyNotificationTask(Context context) {

        Log.e("Ejecutandose", "tarea");

    }

    @Override
    protected Void doInBackground(String... strings)
    {

        Log.e("EJECUTANDOSE", "TAREA");

        UsuariosSQLiteHelper lecturabd = new UsuariosSQLiteHelper(contexto, UsuariosSQLiteHelper.TABLE_NAME_USUARIOS, null, 1);
        SQLiteDatabase db = lecturabd.getWritableDatabase();
        ContentValues values = new ContentValues();
        //values.put(LecturasColumnas.Columnas.COLUMN_NAME_ID, id);
        values.put("username", "tello");
        if (db != null) {
            Long todobien = db.insert(UsuariosSQLiteHelper.TABLE_NAME_USUARIOS, null, values);
        }

        String selectQuery1 = "SELECT * FROM " + UsuariosSQLiteHelper.TABLE_NAME_USUARIOS;
        Cursor cursor1 = db.rawQuery(selectQuery1, null);
        Integer cantidad1 = cursor1.getCount();
        int i = 0;
        if (cantidad1 > 0) {
            cursor1.moveToFirst();
            while (cursor1.isAfterLast() == false) {
                i++;
                String usuario = cursor1.getString(cursor1.getColumnIndex("username"));
                Log.e("Username: ", usuario);
                cursor1.moveToNext();
            }
            cursor1.close();
        }
        db.close();
        return null;
    }


}

Thanks for your help

The error is thrown to me in this line

UsuariosSQLiteHelper lecturabd = new UsuariosSQLiteHelper(contexto, UsuariosSQLiteHelper.TABLE_NAME_USUARIOS, null, 1);

Error:

Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase android.content.Context.openOrCreateDatabase (java.lang.String, int, android.database.sqlite.SQLiteDatabase $ CursorFactory, android.database.DatabaseErrorHandler) 'on a null object reference

android android-studio android-asynctask android-sqlite

asked by desarrollosTELLO 11.09.2018 в 16:24

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1 answer

Error "Maximum call stack size exceeded" when using a component with fetch insert records from an excel file to a DB MS access delphi

score 0 · Answer 1

The problem is that the context you use to instantiate UsuariosSQLiteHelper has a null value:

...
   @Override
    protected Void doInBackground(String... strings)
    {

        Log.e("EJECUTANDOSE", "TAREA");

        UsuariosSQLiteHelper lecturabd = new UsuariosSQLiteHelper(contexto, UsuariosSQLiteHelper.TABLE_NAME_USUARIOS, null, 1);

...
...

The context is obtained in the onReceive(Context context, Intent intent) method and you must send it to MyNotificationTask to be used when instantiating UsuariosSQLiteHelper , make this change:

public class CheckReclamosReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        new MyNotificationTask(context).execute();
    }
}

class MyNotificationTask extends AsyncTask<String, String, Void>{

    //*Agrega variable para almacenar el contexto.
    private Context contexto;

    public MyNotificationTask(Context context) {
        contexto = context; //*** Aquí debes recibir el contexto!
        Log.e("Ejecutandose", "tarea");

    }

    @Override
    protected Void doInBackground(String... strings)
    {

        Log.e("EJECUTANDOSE", "TAREA");

        UsuariosSQLiteHelper lecturabd = new UsuariosSQLiteHelper(contexto, UsuariosSQLiteHelper.TABLE_NAME_USUARIOS, null, 1);
        SQLiteDatabase db = lecturabd.getWritableDatabase();
        ContentValues values = new ContentValues();
        //values.put(LecturasColumnas.Columnas.COLUMN_NAME_ID, id);
        values.put("username", "tello");
        if (db != null) {
            Long todobien = db.insert(UsuariosSQLiteHelper.TABLE_NAME_USUARIOS, null, values);
        }

        String selectQuery1 = "SELECT * FROM " + UsuariosSQLiteHelper.TABLE_NAME_USUARIOS;
        Cursor cursor1 = db.rawQuery(selectQuery1, null);
        Integer cantidad1 = cursor1.getCount();
        int i = 0;
        if (cantidad1 > 0) {
            cursor1.moveToFirst();
            while (cursor1.isAfterLast() == false) {
                i++;
                String usuario = cursor1.getString(cursor1.getColumnIndex("username"));
                Log.e("Username: ", usuario);
                cursor1.moveToNext();
            }
            cursor1.close();
        }
        db.close();
        return null;
    }


}