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Understanding the Android issue causing signal 11 (SIGSEGV), code 1 (SEGV_MAPERR) Error after a few seconds

I am running a sensor and location service, the data is passed to the TraceManager file which where it is dealt with and passed to the TraceCWrapper to be mapped to a shared C library .so , It seems the sensor and location data is fine and received in TraceManager, it then is passed into TraceCWrapper, however the app crashes after a few seconds, and the only error line i get is:
A/libc: Fatal signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x8 in tid 29938 (AsyncTask #1), pid 29870 (pp.traceandroid)
public class TraceManager extends AppCompatActivity {
private String TAG = "TraceManager";
private int phoneAngle = 0;
private double initialStepCalibrationOffset;
private int initialPointingAngleDeg = 0;
private int initialAlignmentMode = 0;
private int startingFloorID = 0;
private LatLng startingLatLong;
private double startingAccuracy = 1.0;
private Context context;
private boolean isMagConsistentAtInit = false;
private boolean isMagValid = true;
private Timer callBackTimer;
private String[] contentsStatic;
private String[] contentsDynamic;
private boolean isRunning = false;
private TraceCWrapper traceCWrapper = new TraceCWrapper();
Handler callbackHandler = new Handler();
Runnable callbackRunnable;
//internal use only
private boolean _traceCDontActuallyUse;
// The interval, in seconds, for providing trace updates.
public ObservableDouble updateCallbackInterval = new ObservableDouble(0){
#Override
public void addOnPropertyChangedCallback(#NonNull OnPropertyChangedCallback callback) {
if(isRunning){
stopCallbackTimer();
startCallbackTimer();
}
super.addOnPropertyChangedCallback(callback);
}
};
private double updateCallBackIntervalValue = updateCallbackInterval.get();
/// A Boolean value
public ObservableBoolean allowsBackgroundExecution = new ObservableBoolean(false){
#Override
public void addOnPropertyChangedCallback(#NonNull OnPropertyChangedCallback callback) {
if(isRunning){
stopUpdatingTrace();
startUpdatingTrace();
}
super.addOnPropertyChangedCallback(callback);
}
};
private boolean allowsBackgroundExecutionValue = allowsBackgroundExecution.get();
public TraceManager(Context context){
this.context=context;
}
public TraceManager(){
}
public void initialiseTrace(String[] mapFloors,
String[] initialDynamicMaps,
int phoneRelativeToBodyDegree, //this comes from onboarding?
double updateCallBackIntervalValue,
boolean allowsBackgroundExecutionValue,
double initialStepCalibrationOffset, //standard
String[] iBeaconUUIDs,
int startingFloorID,
LatLng startingLatLong, //this is form the starting node
double startingAccuracy, //
boolean _traceCDontActuallyUse,
int phoneOrientation,
int phoneOrientationUse,
boolean magntometerValid
){
this.contentsStatic = mapFloors;
this.contentsDynamic = initialDynamicMaps;
this.phoneAngle = phoneRelativeToBodyDegree;
this.initialStepCalibrationOffset = initialStepCalibrationOffset;
this.updateCallbackInterval = updateCallbackInterval;
this.allowsBackgroundExecution = allowsBackgroundExecution;
this.isMagValid = magntometerValid;
if(!(iBeaconUUIDs.length <=0)){
LocationProvider.arrayOfUUIDsToDetect = iBeaconUUIDs;
}else{
Log.i(TAG, "TraceManager.init: ignoring ibeaconUIDs, because it is empty. Default used");
};
this.startingFloorID = startingFloorID;
this.startingLatLong = startingLatLong;
this.startingAccuracy = startingAccuracy;
this.initialPointingAngleDeg = phoneOrientation;
this.initialAlignmentMode = phoneOrientationUse;
//internal use only
this._traceCDontActuallyUse = _traceCDontActuallyUse;
}
//Functions
/// Broadcast Receiver to get readings from MotionProvider/service
public void startUpdatingSensors(){
//Start sensor service
Intent startService = new Intent(TraceManager.this, SensorService.class);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
startForegroundService(startService);
} else {
startService(startService);
}
}
/// Starts the generation of trace updates.
public void startUpdatingTrace(){
//Start Sensors
//startUpdatingSensors();
//register for sensorBroadcast
BroadcastReceiver sensorReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Log.d(TAG, "imu Received");
TCIMUEvent tcimuEvent = (TCIMUEvent) intent.getSerializableExtra("imu");
traceCWrapper.provideDeviceMotion(tcimuEvent, 1, 90, RotationMode.PortraitYUp);
}
};
LocalBroadcastManager.getInstance(context).registerReceiver(
sensorReceiver, new IntentFilter("imuCreated")
);
//register for locationBroadcast
//register for sensorBroadcast
BroadcastReceiver locationReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Log.d(TAG, "location Received");
TCLocationEvent tcLocationEvent = (TCLocationEvent) intent.getSerializableExtra("locationCreated");
Log.d(TAG, "Inlocation reciever");
traceCWrapper.provideLocation(tcLocationEvent);
}
};
LocalBroadcastManager.getInstance(context).registerReceiver(
locationReceiver, new IntentFilter("locationCreated")
);
Log.d(TAG, "inside updating trace");
//Start CallbackTimer
startCallbackTimer();
}
private void CallbackUpdate() {
/* callbackRunnable = new Runnable(){
#Override
public void run() {
Log.d(TAG, "calling callback");
traceCWrapper.getLatestTraceResult();
callbackHandler.postDelayed(this, 1000);
}
};*/
}
private void startCallbackTimer(){
Log.d(TAG, "I get in here callback");
callbackRunnable = new Runnable(){
#Override
public void run() {
Log.d(TAG, "calling callback");
traceCWrapper.getLatestTraceResult();
callbackHandler.postDelayed(this, 1000);
}
};
callbackHandler.postDelayed(callbackRunnable, 1000);
}
private void stopCallbackTimer(){
callbackHandler.removeCallbacks(callbackRunnable);
}
//Calls TraceCWrapper upadate maps and passes the dynamic maps
/* public void updateMaps(String[] dynamicMaps){
traceCWrapper.updateMaps(dynamicMaps dynamicmaps){
}
}*/
public void stopUpdatingTrace(){
boolean stopSensors = true;
if(stopSensors){
stopUpdatingSensors();
}
//Callback Timer
stopCallbackTimer();
//State
isRunning = false;
//Trace terminate
if (_traceCDontActuallyUse == false){
traceCWrapper.terminate();
}
}
private void stopUpdatingSensors() {
//todo
//stop the event bus
//stop the service
}
#RequiresApi(api = Build.VERSION_CODES.O)
public void provideManualLocation(TraceManualLocation manualLocation){
if(isRunning){
}else{
Log.e(TAG, "Calling provideManualLocation, but is running is set to false");
}
if(!_traceCDontActuallyUse){
traceCWrapper.provideManualLocation(manualLocation);
}
}
#RequiresApi(api = Build.VERSION_CODES.O)
public void provideManualHeadingCorrection(TraceManualHeading traceManualHeading){
if(isRunning){
}else{
Log.e(TAG, "Calling provideHeadingCorrection, but is running is set to false");
}
if (!_traceCDontActuallyUse){
traceCWrapper.provideManualHeading(traceManualHeading);
}
}
public void updateParameter(TraceCVarParameter traceCVarParameter, double value){
if(isRunning){
}else{
Log.e(TAG, "Calling updateparameter, but is running is set to false");
}
//todo
//callback async
}
//Private [START]
boolean isInitialised = false;
public boolean isInitialised() {
if(!isInitialised){
}else{
//todo
//send to didfinishinitialisation? confirm isMagConsistentAtInit is true
}
return isInitialised;
}
private boolean isMagConsistantAtInit = false;
private Timer callbackTimer;
/* public traceCallBack(int seconds){
callBackTimer = new Timer();
callBackTimer.schedule(new callUpdate(), seconds*1000);
}*/
class callUpdate extends TimerTask{
#Override
public void run() {
//traceCWrapper.getLatestTraceResult();
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_trace_manager);
}
}
I do not have enough room to add the TraceCWrapper file however the library is loaded as:
static CLibrary lib = Native.loadLibrary("com.waymap.app.traceandroid", CLibrary.class);
And as the main example the method, traceCWrapper.provideDeviceMotion() is received in TraceCWrapper as:
//Provide Device Motion
public static boolean provideDeviceMotion(TCIMUEvent mTCIMUEvent, int Status, double userHeadingDeg, float rotationMode){
DeviceMotion dM = new DeviceMotion();
dM.setTcimuEvent(mTCIMUEvent);
dM.setStatus(Status);
dM.setUserHeadingDeg(userHeadingDeg);
dM.setRotationMode(rotationMode);
if(isRunning) {
new sendToTraceHandleImuEvent().execute(dM);
isInitalized = true;
return isInitalized;
}else{
Log.i(TAG, "IMU update ignored as not running");
isInitalized = false;
return isInitalized;
}
}
public static class sendToTraceHandleImuEvent extends AsyncTask<DeviceMotion,Void,Void>{
#Override
protected Void doInBackground(DeviceMotion... devicemotions) {
/*public class Arg extends Structure {
public devicemotions[] var1 = new byte[9];
public devicemotions[] var2 = new byte[5];
}*/
Log.d(TAG, "InTraceCwrapper Again, provideIMU");
lib.TraceHandleImuEvent(devicemotions[0].getTcimuEvent(), devicemotions[0].getStatus(), devicemotions[0].getUserHeadingDeg(), devicemotions[0].getRotationMode());
return null;
}
}
You will have to excuse the large amount of Logging and excess code as i have been wrestling with this for a while.
When passing my TCIMUEvent i am using the structure annotation as below:
#Structure.FieldOrder({ "time", "accel", "accelValid", "mag", "magValid", "gyro", "gyroValid", "pressure", "pressureValid", "temperature", "temperatureValid"})
public class TCIMUEvent extends Structure implements Serializable {
public double time;
public float[] accel = new float[3];
public boolean accelValid;
public float[] mag = new float[3];
public boolean magValid;
public float[] gyro = new float[3];
public boolean gyroValid;
public float pressure;
public boolean pressureValid;
public float temperature;
public boolean temperatureValid;
public TCIMUEvent(double time, float[] accel, boolean accelValid, float[] mag, boolean magValid, float[] gyro, boolean gyroValid, float pressure, boolean pressureValid, float temperature, boolean temperatureValid) {
this.time = time;
this.accel = accel;
this.accelValid = accelValid;
this.mag = mag;
this.magValid = magValid;
this.gyro = gyro;
this.gyroValid = gyroValid;
this.pressure = pressure;
this.pressureValid = pressureValid;
this.temperature = temperature;
this.temperatureValid = temperatureValid;
}
}
The Java C Mappings that are required:
My Java Library to map:
void TracehandleLocationEvent(TCLocationEvent tcLocationEvent);
void TracehandleManualLocationEvent(TCManualLocationEvent tcManualLocationEvent);
void TracehandleManualHeadingEvent(TCManualHeadingEvent tcManualHeadingEvent);
void TracehandleManualInitialLocation(TCLocationEvent initialLocationEvent);
void TraceHandleImuEvent(TCIMUEvent tcimuEvent, int Status, double userHeadingDeg, float rotationMode);
void TraceGetResult(Double uptime, Pointer traceResult_out);
-------- These map retrospectively to C:---------
void TraceHandleLocationEvent (const Trace_locationSample_t *locationSample)
void TraceHandleManualLocationEvent(const Trace_manualLocationSample_t
*manualLocationSample)
void TraceHandleManualHeadingEvent(const Trace_manualHeadingSample_t
*manualHeadingSample)
void TraceHandleLocationEvent (const Trace_locationSample_t *locationSample)
void TraceHandleImuEvent(Trace_imuDataSample_t *imuDataSample, int *status,
double *userHeadingDeg, StrapdownStreaming_RotationMode *currentRotateMode)
void TraceGetResult(double time, Trace_Result_t *TraceResult)
The new Mappings look like this, the structures for the objects are all the same format as above in the original question:
void TracehandleLocationEvent(TCLocationEvent tcLocationEvent);
void TracehandleManualLocationEvent(TCManualLocationEvent tcManualLocationEvent);
void TracehandleManualHeadingEvent(TCManualHeadingEvent tcManualHeadingEvent);
void TracehandleManualInitialLocation(TCLocationEvent initialLocationEvent);
void TraceGetResult(DoubleByReference uptime, TCResult traceResult_out);
void TraceHandleImuEvent(TCIMUEvent tcimuEvent, IntByReference status, DoubleByReference heading, FloatByReference rotationMode);
The error being thrown now in relation to the empty constructors in my Structure objects:
java.lang.Error: Structure.getFieldOrder() on class com.dataTypes.TCLocationEvent returns names ([altitude, coordinate, horizontalAccuracy, timestamp, verticalAccuracy]) which do not match declared field names ([])
at com.sun.jna.Structure.getFields(Structure.java:1089)
at com.sun.jna.Structure.deriveLayout(Structure.java:1232)
at com.sun.jna.Structure.calculateSize(Structure.java:1159)
at com.sun.jna.Structure.calculateSize(Structure.java:1111)
at com.sun.jna.Structure.allocateMemory(Structure.java:414)
at com.sun.jna.Structure.<init>(Structure.java:205)
at com.sun.jna.Structure.<init>(Structure.java:193)
at com.sun.jna.Structure.<init>(Structure.java:180)
at com.sun.jna.Structure.<init>(Structure.java:172)
at com.dataTypes.TCLocationEvent.<init>(TCLocationEvent.java:30)
at com.locationGetter.LocationService.<clinit>(LocationService.java:39)

SIGSEGV errors with JNA mappings are frequently caused by accessing native memory you don't own. Problems vary, but the first place to look is your structure type mappings and method/function argument mappings.
As one specific example (there may be more), your code includes this mapping:
void TraceHandleImuEvent(TCIMUEvent tcimuEvent, int Status,
double userHeadingDeg, float rotationMode);
However, the native mapping does not expect an int, double, and float here. It expects pointers:
void TraceHandleImuEvent(Trace_imuDataSample_t *imuDataSample, int *status,
double *userHeadingDeg, StrapdownStreaming_RotationMode *currentRotateMode)
(Structures like TCIMUEvent are automatically mapped to their pointers when passed as arguments, so that one's okay.)
What is happening is that you are passing an int for status (e.g., 8) but the native code is thinking "There's an integer stored at memory location 0x8." You don't own that memory, and thus the error.
IntByReference would be the correct type mapping here, and for many of those function arguments.

How to generate a TextView on AsyncTask and place it on a GridLayout?

This is my situation:
I have a GridLayout (wich has some textviews in some cells of it right at the begining of the activity, but i will change it to generate those textviews dynamically later) and I want to place some textViews in a few cells of it.
The problem: I don't know how many textViews I will need. It depends of the information of the database. Besides, I don't know how to add the textViews generated to the gridLayout from an AsyncTask.
So, i've been looking for some answers but I couldn't make it work. I tried something like this, but is not exactly what i'm looking for (i create a new TextView, but can't add it to the gridLayout from that thread).
This is the workflow of my app:
1º I start the activity with the gridLayout. It has some textViews:
This is the main Activity:
public class MostrarProyectos extends AppCompatActivity {
private final String TAG = "MostrarProyectos";
//Para obtener de un hilo no principal los proyectos:
public static ArrayList<Proyecto> listaDeProyectos = new ArrayList<>();
public GridLayout grid;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_mostrar_proyectos);
grid = (GridLayout) findViewById(R.id.grid);
EstrategiaObtenerObjetoDB e = FabricaEstrategiaObtenerDB.getInstance().construirEstrategia("proyecto", this); //This is a Fabric, wich obtains a Strategy
e.execute(this.getApplicationContext(), "proyecto", this, this.grid);//I sended a lot of things to test if something gives result
}
}
2º In that main class, I started a new Thread with AsyncTask, to get data from a SQLite DB.
This is the Fabric:
public class FabricaEstrategiaObtenerDB {
private static final FabricaEstrategiaObtenerDB ourInstance = new FabricaEstrategiaObtenerDB();
public static FabricaEstrategiaObtenerDB getInstance() {
return ourInstance;
}
private FabricaEstrategiaObtenerDB() {}
public EstrategiaObtenerObjetoDB construirEstrategia(String tabla, Activity acti){
switch(tabla){
//Some other cases
case "proyecto":
EstrategiaObtenerObjetoDBProyecto p = new EstrategiaObtenerObjetoDBProyecto(acti, new onTextViewCreatedListener() {
#Override
public void onTextViewCreated(TextView tv) {
//I don't know what to do here
}
}); //This code I tried from the other stackOverflow answer
return p;
default:
return null;
}
}
}
This an abstract class to obtain objects from the DB:
public abstract class EstrategiaObtenerObjetoDB extends AsyncTask<Object, Void, ArrayList<Object>> {
protected onTextViewCreatedListener onTextViewCreatedListener; //part of the code from the other StackOverflow user.
Activity miActividad;
public EstrategiaObtenerObjetoDB(Activity act, onTextViewCreatedListener onTextViewCreatedListener){
this.onTextViewCreatedListener = onTextViewCreatedListener; //This is too code from the other user.
this.miActividad = act;
}
#Override
protected ArrayList<Object> doInBackground(Object... params) {
AppDbHelper mDbHelper = new AppDbHelper(miActividad.getApplicationContext());
SQLiteDatabase db = mDbHelper.getReadableDatabase();
String[] projection = obtenerSelect();
Cursor c = armarQuery(db, (String)params[1], projection); //params[1] is the name of the table in the DB
ArrayList<Object> arrayDeObjetos = new ArrayList<>();
try{
arrayDeObjetos.add(miActividad.getApplicationContext());//add the context
arrayDeObjetos.add(miActividad.findViewById(R.id.grid));//add the grid
armarObjetos(c);
return arrayDeObjetos;
}catch (Exception e){
String b = e.getMessage();
return null;
}
}
#Override
protected abstract void onPostExecute(ArrayList<Object> objects);
protected abstract String[] obtenerSelect();
protected abstract Cursor armarQuery(SQLiteDatabase db, String tabla, String[] projection);
protected abstract void armarObjetos(Cursor c);
}
And this is the specific Strategy:
public class EstrategiaObtenerObjetoDBProyecto extends EstrategiaObtenerObjetoDB {
public EstrategiaObtenerObjetoDBProyecto(Activity act,onTextViewCreatedListener onTextViewCreatedListener) {
super(act,onTextViewCreatedListener);
}
#Override
protected String[] obtenerSelect() {
String[] projection = {
AppContract.Proyecto._ID,
AppContract.Proyecto.COLUMN_NOMBRE,
AppContract.Proyecto.COLUMN_DESCRIPCION,
AppContract.Proyecto.COLUMN_PRIORIDAD,
AppContract.Proyecto.COLUMN_ANIO,
AppContract.Proyecto.COLUMN_MES,
AppContract.Proyecto.COLUMN_SEMANA,
AppContract.Proyecto.COLUMN_DURACION,
};
return projection;
}
#Override
protected Cursor armarQuery(SQLiteDatabase db, String tabla, String[] projection) {
Cursor cursor = db.query(
tabla,
projection,
null,
null,
null,
null,
null
);
return cursor;
}
#Override
protected void armarObjetos(Cursor c) {
c.moveToFirst();
ArrayList<Object> proyectos = new ArrayList<>();
do {
try{
String nombre = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_NOMBRE));
String descripcion = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_DESCRIPCION));
String prioridad = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_PRIORIDAD));
String anio = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_ANIO));
String mes = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_MES));
String semana = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_SEMANA));
String duracion = c.getString(c.getColumnIndex(AppContract.Proyecto.COLUMN_DURACION));
Proyecto p = new Proyecto(nombre,descripcion, prioridad, anio, mes, semana, duracion);
MostrarProyectos.listaDeProyectos.add(p);
proyectos.add(p);
}catch(Exception e){
Log.d("EstrategiaObtenerPr",e.getMessage());
}
} while (c.moveToNext());
}
#Override
protected void onPostExecute(ArrayList<Object> objects) {
MostrarProyectos.listaDeProyectos.add((Proyecto)objects.get(i));
GridLayout grid = (GridLayout) miActividad.findViewById(R.id.grid);
if(!MostrarProyectos.listaDeProyectos.isEmpty()){
for(int numeroTemporal = 0; numeroTemporal<MostrarProyectos.listaDeProyectos.size();numeroTemporal++){
Proyecto j = MostrarProyectos.listaDeProyectos.get(numeroTemporal);
TextView text = new TextView(miActividad.getApplicationContext());
text.setText(j.getNombre());
int numFila = MostrarProyectos.contarFilas(j.getMes(), j.getSemana());
GridLayout.LayoutParams params3 = new GridLayout.LayoutParams();
params3.rowSpec = GridLayout.spec(numFila);//,Integer.parseInt(j.getDuracion())
Log.d("MostrarProyecto", numFila+","+Integer.parseInt(j.getDuracion()));
params3.columnSpec = GridLayout.spec(3);
text.setLayoutParams(params3);
try{
if(onTextViewCreatedListener!=null){
onTextViewCreatedListener.onTextViewCreated(text);//from the other user
}
}catch (Exception excepcion){
Log.d("MostrarProyecto", excepcion.getMessage());
}
}
}
else{
Toast.makeText(miActividad.getApplicationContext(),"No hay proyectos",Toast.LENGTH_LONG);
}
MostrarProyectos.terminoCargaDatos = true;
}
}
3º After I get the data, I want to generate as many TextViews as objects i've got from the DB, so I use a 'for' to see how many objects i have inside a temporal list i created. For heach object, I want to create a TextView, and add it to the gridLayout (that is on the main thread).
And finally, an interface from the other answer:
public interface onTextViewCreatedListener {
public void onTextViewCreated(TextView tv);
}
I hope you can help me. Thank you.
EDIT_1: I need to use other thread different from the UI thread because i need to search in the DB the data.

You have to split your logic, search data in the DB in AsyncTask or simple new Thread() and then create UI elements and attach them in UI thread.
mActivity
.runOnUiThread(
new Runnable() {
#Override
public void run() {
//create a TextView, and add it to the gridLayout
}
});

how to solve android service has leaked error

I have an activity that calls a service on its onCreate , however when I try yo run the project I keep getting an error saying the service has leaked and longer bound on the activity that called/registered it .
"Activity com.xera.deviceinsight.home.DataUsageActivity has leaked ServiceConnection com.xera.deviceinsight.home.DataUsageActivity$3#42676a48 that was originally bound here" I am assuming this might have something to do with the lifecycle of the activity . I have both the activity and the service in question below
myActivity
public class DataUsageActivity extends AppCompatActivity implements MonitorService.ServiceCallback
{
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
TinyDB settings = new TinyDB(this);
if (settings.getBoolean(AppPreferences.HAS_LOGGED_IN))
{
this.bindService(
new Intent(this, MonitorService.class),
serviceConnection,
Context.BIND_AUTO_CREATE);
return;
}
}
public void sendResults(int resultCode, Bundle b)
{
// adapter.notifyDataSetChanged();
}
private ServiceConnection serviceConnection = new ServiceConnection()
{
#Override
public void onServiceConnected(ComponentName className, IBinder service)
{
MonitorService.LocalBinder binder = (MonitorService.LocalBinder)service;
backgroundService = binder.getService();
backgroundService.setCallback(DataUsageActivity.this);
backgroundService.start();
}
#Override
public void onServiceDisconnected(ComponentName className)
{
backgroundService = null;
}
};
#Override
public void onResume()
{
super.onResume();
if(backgroundService != null)
{
backgroundService.setCallback(this);
}
}
#Override
public void onPause()
{
super.onPause();
if(backgroundService != null)
{
backgroundService.setCallback(null);
}
}
}
**myService**
public class MonitorService extends Service
{
private boolean initialized = false;
private final IBinder mBinder = new LocalBinder();
private ServiceCallback callback = null;
private Timer timer = null;
private final Handler mHandler = new Handler();
private String foreground = null;
private ArrayList<HashMap<String,Object>> processList;
private ArrayList<String> packages;
private Date split = null;
// private Date startTime = null;
public int timeCheckVariable = 0 ;
public static int SERVICE_PERIOD = 5000; // TODO: customize (this is for scan every 5 seconds)
private final ProcessList pl = new ProcessList(this)
{
#Override
protected boolean isFilteredByName(String pack)
{
// TODO: filter processes by names, return true to skip the process
// always return false (by default) to monitor all processes
return false;
}
};
public interface ServiceCallback
{
void sendResults(int resultCode, Bundle b);
}
public class LocalBinder extends Binder
{
MonitorService getService()
{
// Return this instance of the service so clients can call public methods
return MonitorService.this;
}
}
#Override
public void onCreate()
{
super.onCreate();
initialized = true;
processList = ((DeviceInsightApp)getApplication()).getProcessList();
packages = ((DeviceInsightApp)getApplication()).getPackages();
}
#Override
public IBinder onBind(Intent intent)
{
if(initialized)
{
return mBinder;
}
return null;
}
public void setCallback(ServiceCallback callback)
{
this.callback = callback;
}
// private boolean addToStatistics(String target , Long startTime)
private boolean addToStatistics(String target )
{
boolean changed = false;
Date now = new Date();
if(!TextUtils.isEmpty(target))
{
if(!target.equals(foreground))
{
int i;
// timeCheckVariable = i ;
if(foreground != null && split != null)
{
// TODO: calculate time difference from current moment
// to the moment when previous foreground process was activated
i = packages.indexOf(foreground);
timeCheckVariable = i ;
long delta = (now.getTime() - split.getTime()) / 1000;
Long time = (Long)processList.get(i).get(ProcessList.COLUMN_PROCESS_TIME);
if(time != null)
{
// TODO: add the delta to statistics of 'foreground'
time += delta;
}
else
{
time = new Long(delta);
}
processList.get(i).put(ProcessList.COLUMN_PROCESS_TIME, time);
//String applicationName = (String)processList.get(i).get(ProcessList.COLUMN_PROCESS_NAME);
// DatabaseHandler db = new DatabaseHandler(this);
// int x = time.intValue( );
// db.addAppRecord(new AppUsageClass(applicationName , x));
// db.getApplicationCount();
// List<AppUsageClass> appUsageClass = db.getAllApplications();
// db.getApplicationCount();
// for (AppUsageClass cn : appUsageClass) {
//String log = "Id: " + cn.getID() + " ,ApplicationName : " + cn.getName() + " ,TimeSpent: " + cn.getTimeSpent();
// Log.d("Name: ", log);
//}
}
//update count of process activation for new 'target'
i = packages.indexOf(target);
Integer count = (Integer)processList.get(i).get(ProcessList.COLUMN_PROCESS_COUNT);
if(count != null) count++;
else
{
count = new Integer(1);
}
processList.get(i).put(ProcessList.COLUMN_PROCESS_COUNT, count);
foreground = target;
split = now;
changed = true;
}
}
//Long checkTimeNow = (Long)processList.get(timeCheckVariable).get(ProcessList.COLUMN_PROCESS_TIME);
return changed;
}
public void start()
{
if(timer == null)
{
timer = new Timer();
timer.schedule(new MonitoringTimerTask(), 500, SERVICE_PERIOD);
}
// TODO: startForeground(srvcid, createNotification(null));
}
public void stop()
{
timer.cancel();
timer.purge();
timer = null;
}
private class MonitoringTimerTask extends TimerTask
{
#Override
public void run()
{
fillProcessList();
ActivityManager activityManager = (ActivityManager)MonitorService.this.getSystemService(ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> taskInfo = activityManager.getRunningTasks(1);
String current = taskInfo.get(0).topActivity.getPackageName(); // gets the application which is in the foreground
int i = packages.indexOf(current);
Long timecheck = (Long)processList.get(i).get(ProcessList.COLUMN_PROCESS_TIME);
if(addToStatistics(current)&& callback != null)
{
final Bundle b = new Bundle();
// TODO: pass necessary info to UI via bundle
mHandler.post(new Runnable()
{
public void run()
{
callback.sendResults(1, b);
}
});
}
}
}
private void fillProcessList()
{
pl.fillProcessList(processList, packages);
}

The problem is that you don't unbind from you service in .onPause() or in .onDestroy(), so if you Activity is destroyed, connection still last, so there is leaked connection. If you want you service to run all the time, you should start it by .startService() and then bind to it. In .onStop() or .onDestroy() unbind from that service

How do I properly execute database calls on other threads?

I am really confused how I should be using threads in my Android applications for database interaction. There are too many resources and I don't know which to choose from. So I'm hoping to get more specific and focused advice on my particular situation so I have a starting point.
This is my database class structure, which works great so far:
public class DatabaseHelper extends SQLiteOpenHelper {
private static volatile SQLiteDatabase mDatabase;
private static DatabaseHelper mInstance = null;
private static Context mContext;
private static final String DB_NAME = "database.db";
private static final int DB_VERSION = 1;
private static final DB_CREATE_THINGY_TABLE = "CREATE TABLE blahblahblah...";
//other various fields here, omitted
public static synchronized DatabaseHelper getInstance(Context context) {
if (mInstance == null) {
mInstance = new DatabaseHelper(context.getApplicationContext());
try {
mInstance.open();
}
catch (SQLException e) {
e.printStackTrace();
}
}
return mInstance;
}
private DatabaseHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
mContext = context;
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DB_CREATE_THINGY_TABLE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
#Override
public void onConfigure(SQLiteDatabase db){
super.onConfigure(db);
db.setForeignKeyConstraintsEnabled(true);
}
public void open() throws SQLException {
mDatabase = getWritableDatabase();
}
public void close() {
mDatabase.close();
}
public long addNewThingy(String name) {
ContentValues values = new ContentValues();
values.put(DatabaseHelper.THINGY_COLUMN_NAME, name);
return mDatabase.insertWithOnConflict(DatabaseHelper.THINGY_TABLE, null, values, SQLiteDatabase.CONFLICT_IGNORE);
}
public Thingy getThingyById(long id) {
Cursor cursor = mDatabase.query(
DatabaseHelper.THINGY_TABLE, // table
new String[]{DatabaseHelper.THINGY_COLUMN_ID, DatabaseHelper.THINGY_COLUMN_NAME}, // column names
DatabaseHelper.THINGY_COLUMN_ID + " = ?", // where clause
new String[]{id + ""}, // where params
null, // groupby
null, // having
null); // orderby
cursor.moveToFirst();
Thingy thingy = null;
if (!cursor.isAfterLast()) {
String name = getStringFromColumnName(cursor, DatabaseHelper.THINGY_COLUMN_NAME);
thingy = new Thingy(id, name);
cursor.moveToNext();
}
cursor.close();
return thingy;
}
}
So any time I want access to the database I do mDatabaseHelper = DatabaseHelper.getInstance(context); and I am good to go. I don't make any explicit calls to open() or close() or anything like that. However right now I am making all my database calls on the UI thread, I believe (either in my onCreate or onCreateView methods or separate methods which don't invoke any new threads or anything).
How would I correctly make this threaded so that I am not performing database operations on the UI thread?
I figure I have to change all my database calls to basically do this:
Make any necessary edits to my database class first to ensure it will work properly in the event that multiple threads are trying to perform operations at the same time. I already tried by making my class a singleton (I think it's a singleton, anyway?) and using keywords like "volatile" and "synchronized" but maybe I am missing something somewhere.
Perform database operation in its own thread.
Somehow trigger additional code back in the appropriate function/activity/fragment that will execute once the database operation has completed.
Make this whole process versatile enough to where I can do it anywhere.
Am I making sense? Is this the right way to be going about all this? Is there a simple example you can make that can show me how to, for example, correctly do something like mThingy = mDatabaseHelper.getThingyById(id); or mDatabaseHelper.addNewThingy(someName); from a sample activity/fragment/etc using proper threading?

Simple solution using Threads
public class DatabaseHelper extends SQLiteOpenHelper {
//...
public void addNewThingyAsync(final String name, final Callback<Long> cb) {
new Thread(new Runnable(){
#Override
public void run(){
cb.callback(addNewThingy(name));
}
}).start();
}
private synchronized long addNewThingy(String name){
//implementation...
}
public void getThingyByIdAsync(final long id, final Callback<Thingy> cb) {
new Thread(new Runnable(){
#Override
public void run(){
cb.callback(getThingyById(id));
}
}).start();
}
private synchronized Thingy getThingyById(long id) {
//implementation...
}
public interface Callback<T> {
public void callback(T t);
}
}
Solution using AsyncTasks
Same as above with the following changes:
public class DatabaseHelper extends SQLiteOpenHelper {
//...
public void addNewThingyAsync(final String name, final Callback<Long> cb) {
new AsyncTask<Void, Void, Long>(){
#Override
protected Long doInBackground(Void... ignoredParams) {
return addNewThingy(name);
}
#Override
protected void onPostExecute(Long result) {
cb.callback(result);
}
}.execute();
}
//...
public void getThingyByIdAsync(final long id, final Callback<Thingy> cb) {
new AsyncTask<Void, Void, Thingy>(){
#Override
protected Thingy doInBackground(Void... ignoredParams) {
return getThingyById(id);
}
#Override
protected void onPostExecute(Thingy result) {
cb.callback(result);
}
}.execute();
}
//...
}
Calling (works with both approaches)
long mId = ...;
mDatabaseHelper = DatabaseHelper.getInstance(context);
mDatabaseHelper.getThingyByIdAsync(mId, new Callback<Thingy>{
#Override
public void callback(Thingy thingy){
//do whatever you want to do with thingy
}
});

How would I correctly make this threaded so that I am not performing
database operations on the UI thread?
Simply perform any database operations off the UI thread. A common technique involves an AsyncTask. For example:
public class GetThingyTask extends AsyncTask<Long, Void, Thingy> {
private Context context;
public AddTask(Context context){
this.context = context;
}
#Override
protected Thingy doInBackground(Long... ids) {
final long id = ids[0];
Cursor cursor = DatabaseHelper.getInstance(context).query(
DatabaseHelper.THINGY_TABLE,
new String[]{
DatabaseHelper.THINGY_COLUMN_ID,
DatabaseHelper.THINGY_COLUMN_NAME
},
DatabaseHelper.THINGY_COLUMN_ID + "=?",
new String[]{String.valueOf(id)},
null, null, null);
String name = null;
if (cursor.moveToFirst() && (cursor.getCount() > 0)) {
name = getStringFromColumnName(cursor, DatabaseHelper.THINGY_COLUMN_NAME);
}
cursor.close();
return new Thingy(id, name);
}
#Override
protected void onPostExecute(Thingy thingy) {
//Broadcast the Thingy somehow. EventBus is a good choice.
}
}
And to use it (inside, for example, an Activity):
new GetThingyTask(this).execute(id);

Is is possible to make a method execute only once?

I have a for loop and structure like this:
for(....)
....
....
if(isTrue)
... do something..
.. method to be executed once (doTrick) is declared outside for loop.
....endif
endfor
public void doTrick()
...
...
..end
Is it possible for a method in for loop to be executed only once?

Sure!..
if(!alreadyExecuted) {
doTrick();
alreadyExecuted = true;
}

Your can use AtomicBoolean to make sure the task is only called the first time:
import java.util.concurrent.atomic.AtomicBoolean;
public class Once {
private final AtomicBoolean done = new AtomicBoolean();
public void run(Runnable task) {
if (done.get()) return;
if (done.compareAndSet(false, true)) {
task.run();
}
}
}
Usage:
Once once = new Once();
once.run(new Runnable() {
#Override
public void run() {
foo();
}
});
// or java 8
once.run(() -> foo());

if you use kotlin, you can do this:
val execOnce by lazy {
print("hello, world")
}

In Java 8, you can effectively do this using automatic memoization as described here: Do it in Java 8: Automatic memoization
I'll admit that memoization could be considered overkill for a "run once" scenario, but it is a rather clean alternative to some described in previous answers.
For instance:
public void doSomething() { ... }
Map<Boolean, Boolean> cache = new ConcurrentHashMap<>();
public void doSomethingOnce() {
cache.computeIfAbsent(true, x -> {
doSomething();
return true;
});
}

You can avoid the if() by using this trick:
private Runnable once;
private final static Runnable NOP = new Runnable () {
public void run () {
// Do nothing
}
}
public void method () {
once = new Runnable () {
public void run () {
doTrick();
once = NOP;
}
}
for (...) {
...
once.run();
...
}
}

Another overkill solution:
Depending on what you want to do, it might be possible to use a static initialization block.
public class YourKlass{
public void yourMethod(){
DoTrick trick;
for( int i = 0; condition; i++){
// ... (1)
trick = new DoTrick(); // or any kind of accessing DoTrick
// ... (2)
}
}
}
public class DoTrick{
static{
// Whatever should be executed only once
}
}
Simple solution:
Or, instead you just want to execute the first part outside of the loop:
int i = 0;
if( condition ){
// ... (1)
// do trick
// ... (2)
}
for(i = 1; condition; i++){
// ... (1)
// ... (2)
}

perhaps the break keyword is what you need? After running you method call break; I am sorry its not 100% clear what you mean from your question.
Have a look here from the sun docs

my sample from my app:
boolean alreadyExecuted = false;
then :
private void startMyService() {
if(!alreadyExecuted) {
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
//Do something after 4 seconds
context.startService(new Intent(context, myService.class));
alreadyExecuted = true;
}
}, 4000);
}

I want to do something slight more complex. In a multi-threaded environment ensure that the methods is run only one (which is solved by Hover Ruan's answer above), but also block any thread so none return until the method is done.
My solution is to use a Semaphore to do the blocking.
public class Once implements Runnable {
private static Semaphore signal = new Semaphore(1,true);
private static boolean done=false;
#Override
public void run() {
if(done)
return;
signal.acquireUninterruptibly();
if(done) {
signal.release();
return;
}
doTrick(); // actually run the task
done=true;
signal.release();
return;
}
static int result; // Result of running the task
static int count; // number of times its been called
/**
* The task we only want to run once
*/
public void doTrick() {
++count;
Random rnd = new Random();
for(int i=0;i<10000;++i) {
result += rnd.nextInt(100);
}
try {
Thread.sleep(1000); // just to ensure all thread start
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
ExecutorService executor = Executors.newFixedThreadPool(10);
for(int i=0;i<5;++i) { // multiple instances
final Once task = new Once();
for(int j=0;j<5;++j) { // multiple calls of same instance
executor.submit(() -> {
task.run();
System.out.println("Result "+Once.result+" count "+Once.count);
} );
}
}
executor.shutdown();
try {
executor.awaitTermination(1, TimeUnit.MINUTES);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
The program should pause, waiting until the first thread has finished, then all other threads should finish printing the result stored from the first run.

or by using Shared Preferences:
sharedpref = PreferenceManager.getDefaultSharedPreferences(this);
isFirstRun = sharedpref.getBoolean("FIRSTRUN", true);
if (isFirstRun)
{
// Do your unique code magic here
SharedPreferences.Editor editor = wmbPreference.edit();
editor.putBoolean("FIRSTRUN", false);
editor.commit();
}else{
//this will repeat everytime
}

Here is an example way. Just use "new Getlineonce();"
class Getlineonce {
static int[] linesRun = new int[0];
public Getlineonce() {
boolean lineRan = false;
int line = Thread.currentThread().getStackTrace()[2].getLineNumber();
for(int i = 0; i < linesRun.length; i++) {
if(line == linesRun[i]) {
lineRan = true; //Dont print
}
}
if(!lineRan) {
add(line);
System.out.println(line + " ran!");
}
}
public void add(int line) {
int newSize = linesRun.length+1;
int[] linesRunBuff = new int[newSize];
for(int i = 0; i < newSize-1; i++) {
linesRunBuff[i] = linesRun[i];
}
linesRunBuff[newSize-1] = line;
linesRun = linesRunBuff;
}
}

For me, the perfect solution was...
public class MainActivity extends BaseActivity {
private static boolean splash = false;
if (!splash){
runSplash();
}
private void runSplash(){
MainActivity.splash = true;
}
}
Defined my variable as private static and use the access via class.variable in my function :)

Try this. First, this will be called only once when the app is being installed for the first time on the user's device. Use SharedPreferences this will help us to remember that this method has already been called so it will not re-call it again when the app is killed or even if the device was turned off. (But keep in mind that when the user un-stall and then re-install the app the method will be called again)
public class MainActivity extends AppCompatActivity {
private static boolean alreadyExecuted = false; // Use private static boolean
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this); // Use SharedPreferences
if (!prefs.getBoolean("onlyonce", false)) {
startMyService(); // Method to be called only once as long as the app wont be un-stalled but there is
// no problem if the app will be killed or the device being turned off.
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("onlyonce", true);
editor.commit();
}
}
private void startMyService() {
if (!alreadyExecuted) {
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
Intent intent = new Intent(MainActivity.this, SecondActivity2.class);
startActivity(intent);
alreadyExecuted = true;
}
}, 4000);
}
}
}

import java.util.ArrayList;
class RemoveDuplicate {
public static void main(String[] args) {
ArrayList<String> originalList = new ArrayList<String>();
originalList.add("foo");
originalList.add("bar");
originalList.add("bat");
originalList.add("baz");
originalList.add("bar");
originalList.add("bar");
String str="bar";
ArrayList<String> duplicateList = new ArrayList<String>();
// adding duplicates to duplicateList
for(String currentString : originalList) {
if(currentString.startsWith(str)) {
duplicateList.add(currentString);
}
}
// removing duplicates in duplicatesList
for(String removeString : duplicateList) {
originalList.remove(removeString);
}
// finally adding duplicateElement
originalList.add(str);
for(String currEntry : originalList) {
System.out.println(currEntry);
}
}
}