Develop Reference

v3 library in app purchase: How to make download possible | Android

My problem is that I don't know how to make a download of the upgrade version possible and I don't know where I must put the code of the upgrade version.
This is my code from https://github.com/anjlab/android-inapp-billing-v3:
BillingProcessor bp;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.upgrade);
setTitle("Upgrade");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
bp = new BillingProcessor(this, "/*Here's my license key from GooglePlay*/", this);
Button buy = (Button) findViewById((R.id.buy));
buy.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick (View view) {
bp.purchase(upgrade.this, "upgrade");
}
});
}
// IBillingHandler implementation
#Override
public void onBillingInitialized() {
/*
* Called when BillingProcessor was initialized and it's ready to purchase
*/
}
#Override
public void onProductPurchased(String productId, TransactionDetails details) {
/*
* Called when requested PRODUCT ID was successfully purchased
*/
}
#Override
public void onBillingError(int errorCode, Throwable error) {
/*
* Called when some error occurred. See Constants class for more details
*
* Note - this includes handling the case where the user canceled the buy dialog:
* errorCode = Constants.BILLING_RESPONSE_RESULT_USER_CANCELED
*/
}
#Override
public void onPurchaseHistoryRestored() {
/*
* Called when purchase history was restored and the list of all owned PRODUCT ID's
* was loaded from Google Play
*/
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (!bp.handleActivityResult(requestCode, resultCode, data)) {
super.onActivityResult(requestCode, resultCode, data);
}
}
#Override
public void onDestroy() {
if (bp != null) {
bp.release();
}
super.onDestroy();
}
My question is now how to make a download of this upgrade possible? Where must be the code of the upgrade version?
Thanks for answering!

Android layout is not being displayed when input is required

I have an app that uses several activities. One activity is to manually enter some values and I have four buttons in that activity. When one of the buttons is clicked it starts a new activity to get the input.
The problem is that the layout for the activity is not displayed when the get_input() function of this activity is run. It should get a decimal value from an EditText. but I keep getting a runtime error of "Invalid Float """.
If I comment out the get_input() function then the layout for the activity is shown fine.
Here is the xml file :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/manually_entry" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Please enter the decimal Latitude"
android:singleLine="true"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Negative is South"
android:singleLine="true"
/>
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:inputType="numberDecimal|numberSigned"
android:id="#+id/enter_decimal_number" />
</LinearLayout>
And here is the calling activity :
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.lat_long_manual_entry);
}
// manual entry dialog buttons
public void enter_lat_dec_deg(View v) {
Intent intent = new Intent(this.getApplicationContext(), ManuallyEnterNumbers.class);
startActivity(intent);
}
And here is the called activity that requests the actual input from the user :
package com.example.david.gpstest;
import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;
/**
* Created by david on 06/03/16.
*/
public class ManuallyEnterNumbers extends Activity {
private EditText input;
private float decimal_input;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.manually_enter_numbers);
}
#Override
protected void onStart() {
super.onStart();
}
#Override
protected void onResume() {
super.onResume();
get_input();
}
public void get_input() {
input = (EditText) findViewById(R.id.enter_decimal_number);
input.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_DONE) {
decimal_input = Float.valueOf(input.getText().toString());
return true;
}
return false;
}
});
}
}
I am showing the function get_input() in the onStart() method but IO have also tried it in the onResume() method and that does not work either.
Any help here would be very much appreciated.
Thank You.

Float.valueOf(input.getText().toString());
The common mistake here newbies ofter make is lack of string sanitization prior attempting conversion. Even , (comma) instead of . (dot) entered as decimal part separator will cause exception to be thrown. So you simply must make string convertable (i.e. by checking what's inside, replacing , with . etc) not to mention you should expect exception to come and use try/catch to catch it to avoid app crash you are facing now.

David, hello, this is yourself. Basically you can forget about sanitizing the input. Because you have android:inputType="numberDecimal|numberSigned" in your xml you will get a numeric keypad with the comma, and space disabled. So all that the user can enter is digits a decimal point and a minus sign. Exactly what you want. Secondly, you can forget about the onStart() and onResume() methods and stick everything in onCreate() and then it will work. Your xml is absolutely fine. Your calling activity absolutely fine too although it would be a good idea to use an intent.putExtra() and an intent.getExtra() to pass the decimal_input value back to the calling activity. I have posted the code for the calling activity and the called activity below to help you out a bit.
public class ManualEntry extends Activity {
// private View layout;
// private PopupWindow enter_manual_dec_deg;
// LayoutInflater inflater;
// private EditText input;
// private float decimal_input;
// private String result;
static final int REQUEST_CODE = 1;
String button_pressed;
/**
* Called when the activity is first created.
*/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.lat_long_manual_entry);
}
#Override
protected void onResume() {
super.onResume();
}
// manual entry dialog buttons
public void enter_lat_dec_deg(View v) {
Intent intent = new Intent(this.getApplicationContext(), ManuallyEnterNumbers.class);
button_pressed = "lat_dec_deg";
intent.putExtra("Button pressed", button_pressed);
startActivityForResult(intent, REQUEST_CODE);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == REQUEST_CODE) {
if (resultCode == RESULT_OK) {
double result = data.getDoubleExtra("returnData", 0.0d);
if (result < -180 || result > 180) {
Toast.makeText(this, "Value outside range - Range is -180 to 180", Toast.LENGTH_LONG).show();
}
else {
DecimalFormat var = new DecimalFormat("###.########");
Toast.makeText(this, var.format(result), Toast.LENGTH_LONG).show();
disable_button(button_pressed);
}
}
}
}
void disable_button(String pressed_button) {
Button dec_deg_button = (Button) findViewById(R.id.button_lat_dec_deg);
Button d_m_s_button = (Button) findViewById(R.id.button_lat_deg_min_sec);
if (pressed_button != null) {
if (pressed_button == "lat_dec_deg" || button_pressed == "lat_d_m_s") {
dec_deg_button.setEnabled(false);
d_m_s_button.setEnabled(false);
}
}
}
}
/*
public void enter_lat_d_m_s (View v) {
}
public void enter_lon_dec_deg(View v) {
}
public void enter_lon_d_m_s(View v) {
}
*/
And the called activity
package com.example.david.gpstest;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
/**
* Created by david on 06/03/16.
*/
public class ManuallyEnterNumbers extends Activity {
private EditText input;
private String inValue;
private double decimal_input;
private Bundle extras;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.manually_enter_numbers);
extras = getIntent().getExtras();
if (extras != null) {
String buttonPressed = extras.getString("Button pressed");
if (buttonPressed.contentEquals(buttonPressed) ) {
((TextView) findViewById(R.id.enter_decimal_number)).setHint("Decimal degrees of Latitude");
TextView title_text = (TextView) findViewById(R.id.manual_entry_hint);
title_text.setText("Please enter the decimal Latitude");
TextView hint_text = (TextView) findViewById(R.id.manual_entry_hint);
hint_text.setText("(Negative is South)");
}
}
get_input();
}
#Override
protected void onStart() {
super.onStart();
// get_input();
}
#Override
protected void onResume() {
super.onResume();
// get_input();
}
public void get_input() {
input = (EditText) findViewById(R.id.enter_decimal_number);
input.setOnEditorActionListener(new TextView.OnEditorActionListener(){
#Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_DONE) {
// do stuff here
inValue = input.getText().toString();
if (inValue.isEmpty()) {
Toast.makeText(getApplicationContext(), "Enter a value", Toast.LENGTH_SHORT).show();
}
else {
// some input
decimal_input = Double.parseDouble(inValue);
Intent returnIntent = getIntent();
returnIntent.putExtra("returnData", decimal_input);
setResult(RESULT_OK, returnIntent);
finish();
}
}
return true;
}
});
/*
Intent returnIntent = getIntent();
returnIntent.putExtra("returnData", decimal_input);
setResult(RESULT_OK, returnIntent);
finish();
*/
}
}
I hope that this helps you out a bit.
David.

Using Activity Recognition

I want to implement an app which needs to implement activity recognition i studied and followed the steps which are in developer.android.com whenever i am running the code it continuously showing "Launching Activity Recognition(it is my app name)" instead to show the app running.If i click anything on the eclipse it just stuck and closing the window
Is there anything i have to do?
Here is my code
package com.example.activityrecignition;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.IntentService;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.IntentSender.SendIntentException;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks;
import com.google.android.gms.common.GooglePlayServicesClient.OnConnectionFailedListener;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.location.ActivityRecognitionClient;
import com.google.android.gms.location.ActivityRecognitionResult;
import com.google.android.gms.location.DetectedActivity;
public class MainActivity extends FragmentActivity implements ConnectionCallbacks,OnConnectionFailedListener {
public static final int MILLISECONDS_PER_SECOND = 1000;
public static final int DETECTION_INTERVAL_SECONDS = 20;
public static final int DETECTION_INTERVAL_MILLISECONDS =
MILLISECONDS_PER_SECOND * DETECTION_INTERVAL_SECONDS;
private final static int
CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
private PendingIntent mActivityRecognitionPendingIntent;
// Store the current activity recognition client
private ActivityRecognitionClient mActivityRecognitionClient;
private Context mContext;
private Intent intent;
TextView tv;
ActivityRecognitionIntentService ar;
private boolean mInProgress;
public enum REQUEST_TYPE {START, STOP}
private REQUEST_TYPE mRequestType;
Intent i;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mActivityRecognitionClient =
new ActivityRecognitionClient(mContext, this, this);
mActivityRecognitionPendingIntent =
PendingIntent.getService(mContext, 0, intent,
PendingIntent.FLAG_UPDATE_CURRENT);
tv=(TextView) findViewById(R.id.activityname);
mInProgress=false;
ar.onHandleIntent(i);
}
#SuppressLint("NewApi") public static class ErrorDialogFragment extends DialogFragment {
private Dialog mDialog;
#SuppressLint("NewApi") public ErrorDialogFragment() {
super();
mDialog = null;
}
public void setDialog(Dialog dialog) {
mDialog = dialog;
}
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
return mDialog;
}
public void show(FragmentManager supportFragmentManager, String tag) {
}
}
#Override
protected void onActivityResult(
int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case CONNECTION_FAILURE_RESOLUTION_REQUEST :
switch (resultCode) {
case Activity.RESULT_OK :
break;
}
}
}
private boolean servicesConnected() {
int resultCode =
GooglePlayServicesUtil.
isGooglePlayServicesAvailable(this);
if (ConnectionResult.SUCCESS == resultCode) {
Log.d("Activity Recognition",
"Google Play services is available.");
return true;
} else {
Dialog errorDialog = GooglePlayServicesUtil.getErrorDialog(
resultCode,
this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
if (errorDialog != null) {
// Create a new DialogFragment for the error dialog
ErrorDialogFragment errorFragment =
new ErrorDialogFragment();
// Set the dialog in the DialogFragment
errorFragment.setDialog(errorDialog);
// Show the error dialog in the DialogFragment
errorFragment.show(
getSupportFragmentManager(),
"Activity Recognition");
}
return false;
}
}
public class ActivityRecognitionIntentService extends IntentService {
public ActivityRecognitionIntentService(String name) {
super(name);
// TODO Auto-generated constructor stub
}
private String getNameFromType(int activityType) {
switch(activityType) {
case DetectedActivity.IN_VEHICLE:
return "in_vehicle";
case DetectedActivity.ON_BICYCLE:
return "on_bicycle";
case DetectedActivity.ON_FOOT:
return "on_foot";
case DetectedActivity.STILL:
return "still";
case DetectedActivity.UNKNOWN:
return "unknown";
case DetectedActivity.TILTING:
return "tilting";
}
return "unknown";
}
#Override
protected void onHandleIntent(Intent intent) {
// If the incoming intent contains an update
if (ActivityRecognitionResult.hasResult(intent)) {
// Get the update
ActivityRecognitionResult result =
ActivityRecognitionResult.extractResult(intent);
// Get the most probable activity
DetectedActivity mostProbableActivity =
result.getMostProbableActivity();
/*
* Get the probability that this activity is the
* the user's actual activity
*/
int confidence = mostProbableActivity.getConfidence();
/*
* Get an integer describing the type of activity
*/
int activityType = mostProbableActivity.getType();
String activityName = getNameFromType(activityType);
tv.setText(activityName);
/*
* At this point, you have retrieved all the information
* for the current update. You can display this
* information to the user in a notification, or
* send it to an Activity or Service in a broadcast
* Intent.
*/
} else {
/*
* This implementation ignores intents that don't contain
* an activity update. If you wish, you can report them as
* errors.
*/
tv.setText("There are no updates!!!");
}
}
}
public void onClick(View v){
if(v.getId()==R.id.Start){
startUpdates();
}
if(v.getId()==R.id.Stop){
stopUpdates();
}
}
public void startUpdates() {
// Check for Google Play services
mRequestType = REQUEST_TYPE.START;
if (!servicesConnected()) {
return;
}
// If a request is not already underway
if (!mInProgress) {
// Indicate that a request is in progress
mInProgress = true;
// Request a connection to Location Services
mActivityRecognitionClient.connect();
//
} else {
/*
* A request is already underway. You can handle
* this situation by disconnecting the client,
* re-setting the flag, and then re-trying the
* request.
*/
mInProgress = true;
mActivityRecognitionClient.disconnect();
mActivityRecognitionClient.requestActivityUpdates(
DETECTION_INTERVAL_MILLISECONDS,
mActivityRecognitionPendingIntent);
}
}
#Override
public void onConnected(Bundle dataBundle) {
// TODO Auto-generated method stub
mActivityRecognitionClient.requestActivityUpdates(
DETECTION_INTERVAL_MILLISECONDS,
mActivityRecognitionPendingIntent);
/*
* Since the preceding call is synchronous, turn off the
* in progress flag and disconnect the client
*/
mInProgress = false;
mActivityRecognitionClient.disconnect();
switch (mRequestType) {
case START :
/*
* Request activity recognition updates using the
* preset detection interval and PendingIntent.
* This call is synchronous.
*/
mActivityRecognitionClient.requestActivityUpdates(
DETECTION_INTERVAL_MILLISECONDS,
mActivityRecognitionPendingIntent);
break;
case STOP :
mActivityRecognitionClient.removeActivityUpdates(
mActivityRecognitionPendingIntent);
/*
* An enum was added to the definition of REQUEST_TYPE,
* but it doesn't match a known case. Throw an exception.
*/
default :
try {
throw new Exception("Unknown request type in onConnected().");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
break;
}
}
#Override
public void onDisconnected() {
// TODO Auto-generated method stub
mInProgress = false;
// Delete the client
mActivityRecognitionClient = null;
}
#Override
public void onConnectionFailed(ConnectionResult connectionResult) {
// Turn off the request flag
mInProgress = false;
/*
* If the error has a resolution, start a Google Play services
* activity to resolve it.
*/
if (connectionResult.hasResolution()) {
try {
connectionResult.startResolutionForResult(
this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
} catch (SendIntentException e) {
// Log the error
e.printStackTrace();
}
// If no resolution is available, display an error dialog
} else {
// Get the error code
int errorCode = connectionResult.getErrorCode();
// Get the error dialog from Google Play services
Dialog errorDialog = GooglePlayServicesUtil.getErrorDialog(
errorCode,
this,
CONNECTION_FAILURE_RESOLUTION_REQUEST);
// If Google Play services can provide an error dialog
if (errorDialog != null) {
// Create a new DialogFragment for the error dialog
ErrorDialogFragment errorFragment =
new ErrorDialogFragment();
// Set the dialog in the DialogFragment
errorFragment.setDialog(errorDialog);
// Show the error dialog in the DialogFragment
errorFragment.show(
getSupportFragmentManager(),
"Activity Recognition");
}
}
}
public void stopUpdates() {
// Set the request type to STOP
mRequestType = REQUEST_TYPE.STOP;
/*
* Test for Google Play services after setting the request type.
* If Google Play services isn't present, the request can be
* restarted.
*/
if (!servicesConnected()) {
return;
}
// If a request is not already underway
if (!mInProgress) {
// Indicate that a request is in progress
mInProgress = true;
// Request a connection to Location Services
mActivityRecognitionClient.connect();
//
} else {
/*
* A request is already underway. You can handle
* this situation by disconnecting the client,
* re-setting the flag, and then re-trying the
* request.
*/
}
}
}

Actually i am getting GC overhead limit exceeded problem.I got the solution here

android spinner action bar (easy answer for someone)

Im having trouble adding a spinner in place of the application name in my action bar.
im sure this question has been asked before but all the answers are pretty much the same either a simple one line correction and then a reference to thiers a lovely example at the google dev site here: http://developer.android.com/guide/topics/ui/actionbar.html#Dropdown
the android docs but for a beginner I find it ashumes to much and leaves out tiny peices of key information.
public class MainProgram extends Activity implements OnNavigationListener {
/**
* Mobile Service Client reference
*/
private MobileServiceClient mClient;
private ConnectWithService service;
/**
* Progress spinner to use for table operations
*/
private ProgressBar mProgressBar;
/**
* Sensor stuff
*/
SensorManager mSensor;
Detection orientation;
//Spinner Listener
mOnNavigationListener = new OnNavigationListener() {
// Get the same strings provided for the drop-down's ArrayAdapter
String[] strings = getResources().getStringArray(R.array.action_list);
#Override
public boolean onNavigationItemSelected(int position, long itemId) {
//toast
Toast toast = Toast.makeText(this, "whoop whoop!", toast.LENGTH_SHORT);
toast.show();
}
};
/**
* Initializes the activity
*/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_program);
//Load progress bar view
mProgressBar = (ProgressBar) findViewById(R.id.loadingProgressBar);
// Initialize the progress bar
mProgressBar.setVisibility(ProgressBar.GONE);
//Spinner Adapter
setNavigationMode(NAVIGATION_MODE_LIST);
SpinnerAdapter mSpinnerAdapter = ArrayAdapter.createFromResource(this, R.array.action_list,
android.R.layout.simple_spinner_dropdown_item);
//innitialize Sensor Manager
mSensor = (SensorManager)getSystemService(SENSOR_SERVICE);
//signin
try {
// Create the Mobile Service Client instance, using the provided
// Mobile Service URL and key
mClient = new MobileServiceClient(
"secret",
"secret",
this).withFilter(new ProgressFilter());
} catch (MalformedURLException e) {
createAndShowDialog(new Exception("There was an error creating the Mobile Service. Verify the URL"), "Error");
}
authenticate();
}
/**
* Initializes the activity menu
*/
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
/**
* Select an option from the menu
*/
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.menu_refresh) {
}
return true;
}
/**
* Creates a dialog and shows it
*
* #param exception
* The exception to show in the dialog
* #param title
* The dialog title
*/
private void createAndShowDialog(Exception exception, String title) {
createAndShowDialog(exception.toString(), title);
}
/**
* Creates a dialog and shows it
*
* #param message
* The dialog message
* #param title
* The dialog title
*/
private void createAndShowDialog(String message, String title) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage(message);
builder.setTitle(title);
builder.create().show();
}
private class ProgressFilter implements ServiceFilter {
#Override
public void handleRequest(ServiceFilterRequest request, NextServiceFilterCallback nextServiceFilterCallback,
final ServiceFilterResponseCallback responseCallback) {
runOnUiThread(new Runnable() {
#Override
public void run() {
if (mProgressBar != null) mProgressBar.setVisibility(ProgressBar.VISIBLE);
}
});
nextServiceFilterCallback.onNext(request, new ServiceFilterResponseCallback() {
#Override
public void onResponse(ServiceFilterResponse response, Exception exception) {
runOnUiThread(new Runnable() {
#Override
public void run() {
if (mProgressBar != null) mProgressBar.setVisibility(ProgressBar.GONE);
}
});
if (responseCallback != null) responseCallback.onResponse(response, exception);
}
});
}
}
private void authenticate() {
// Login using the Google provider.
mClient.login(MobileServiceAuthenticationProvider.MicrosoftAccount,
new UserAuthenticationCallback() {
#Override
public void onCompleted(MobileServiceUser user,
Exception exception, ServiceFilterResponse response) {
if (exception == null) {
createAndShowDialog(String.format(
"You are now logged in - %1$2s",
user.getUserId()), "Success");
service = new ConnectWithService(mClient,user.getUserId());
orientation = new Detection(mSensor);
} else {
createAndShowDialog("You must log in. Login Required", "Error");
}
}
});
}
//start sensors camera etc if needed
protected void onResume() {
super.onResume();
if(orientation!=null)
orientation.startSensorsListening();
}
// stop sensors etc
protected void onPause() {
super.onPause();
orientation.stopSensorListening();
}
}
theres at least two errors i think mOnNavigationListener should be somewhere else
setnavigationMode() has an error

don't use OnNavigationListener with (ActionBar.NAVIGATION_MODE_LIST)
use:
final ActionBar bar = getActionBar();
bar.setDisplayShowCustomEnabled(true);
bar.setCustomView(R.layout.action_bar_custom);
then all as normal.
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?>....

Loader unable to retain itself during certain configuration change

According to http://developer.android.com/guide/components/loaders.html, one of the nice thing about loader is that, it is able to retain its data during configuration change.
They automatically reconnect to the last loader's cursor when being
recreated after a configuration change. Thus, they don't need to
re-query their data.
However, it doesn't work well in all scenarios.
I take a following simple example. It is a FragmentActivity, which is hosting a Fragment. The Fragment itself owns the AsyncTaskLoader.
The following 3 scenarios work pretty well.
During first launched (OK)
1 loader is created, and loadInBackground is executed once.
During simple rotation (OK)
No new loader is being created and loadInBackground is not being triggered.
A child activity is launched, and back button pressed (OK)
No new loader is being created and loadInBackground is not being triggered.
However, in the following scenario.
A child activity is launched -> Rotation -> Back button pressed (Wrong)
At that time, old loader's onReset is called. Old loader will be destroyed. New loader will be created and new loader's loadInBackground will be triggered again.
The correct behavior I'm expecting is, no new loader will be created.
The loader related code is as follow. I run the code under Android 4.1 emulator.
package com.example.bug;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.AsyncTaskLoader;
import android.support.v4.content.Loader;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class MainFragment extends Fragment implements LoaderManager.LoaderCallbacks<Integer> {
private static class IntegerArrayLoader extends AsyncTaskLoader<Integer> {
private Integer result = null;
public IntegerArrayLoader(Context context) {
super(context);
Log.i("CHEOK", "IntegerArrayLoader created!");
}
#Override
public Integer loadInBackground() {
Log.i("CHEOK", "Time consuming loadInBackground!");
this.result = 123456;
return result;
}
/**
* Handles a request to cancel a load.
*/
#Override
public void onCanceled(Integer integer) {
super.onCanceled(integer);
}
/**
* Handles a request to stop the Loader.
* Automatically called by LoaderManager via stopLoading.
*/
#Override
protected void onStopLoading() {
// Attempt to cancel the current load task if possible.
cancelLoad();
}
/**
* Handles a request to start the Loader.
* Automatically called by LoaderManager via startLoading.
*/
#Override
protected void onStartLoading() {
if (this.result != null) {
deliverResult(this.result);
}
if (takeContentChanged() || this.result == null) {
forceLoad();
}
}
/**
* Handles a request to completely reset the Loader.
* Automatically called by LoaderManager via reset.
*/
#Override
protected void onReset() {
super.onReset();
// Ensure the loader is stopped
onStopLoading();
// At this point we can release the resources associated with 'apps'
// if needed.
this.result = null;
}
}
#Override
public Loader<Integer> onCreateLoader(int arg0, Bundle arg1) {
Log.i("CHEOK", "onCreateLoader being called");
return new IntegerArrayLoader(this.getActivity());
}
#Override
public void onLoadFinished(Loader<Integer> arg0, Integer arg1) {
result = arg1;
}
#Override
public void onLoaderReset(Loader<Integer> arg0) {
// TODO Auto-generated method stub
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_main, container, false);
return v;
}
// http://stackoverflow.com/questions/11293441/android-loadercallbacks-onloadfinished-called-twice
#Override
public void onResume()
{
super.onResume();
if (result == null) {
// Prepare the loader. Either re-connect with an existing one,
// or start a new one.
getLoaderManager().initLoader(0, null, this);
} else {
// Restore from previous state. Perhaps through long pressed home
// button.
}
}
private Integer result;
}
Complete source code can be downloaded from https://www.dropbox.com/s/n2jee3v7cpwvedv/loader_bug.zip
This might be related to 1 unsolved Android bug : https://code.google.com/p/android/issues/detail?id=20791&can=5&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars
https://groups.google.com/forum/?fromgroups=#!topic/android-developers/DbKL6PVyhLI
I was wondering, is there any good workaround on this bug?

My answer is quite straight forward actually. Don't use AsyncTaskLoaders. Because a few bugs regarding AsyncTaskLoaders you knew it by now.
A good combination would be a retainable (setRetainInstance(true) in onActivityCreated()) fragment with AsyncTask. Works the same way. Just have to restructure the code a bit.
Message from OP
Although the author doesn't provide any code example, this is the closest workable solution. I do not use the author proposed solution. Instead, I still rely on AsyncTaskLoader for all the necessary loading task. The workaround is that, I will rely on an additional retained fragment, to determine whether I should reconnect/create loader. The is the skeleton code on the whole idea. Works pretty well so far as long as I can tell.
#Override
public void onActivityCreated(Bundle savedInstanceState) {
...
dataRetainedFragment = (DataRetainedFragment)fm.findFragmentByTag(DATE_RETAINED_FRAGMENT);
// dataRetainedFragment can be null still...
}
#Override
public void onResume() {
...
if (this.data == null) {
if (dataRetainedFragment != null) {
// Re-use!
onLoadFinished(null, dataRetainedFragment);
} else {
// Prepare the loader. Either re-connect with an existing one,
// or start a new one.
getLoaderManager().initLoader(0, null, this);
}
} else {
}
}
#Override
public void onLoadFinished(Loader<Data> arg0, Data data) {
this.data = data;
if (this.dataRetainedFragment == null) {
this.dataRetainedFragment = DataRetainedFragment.newInstance(this.data);
FragmentManager fm = getFragmentManager();
fm.beginTransaction().add(this.dataRetainedFragment, DATE_RETAINED_FRAGMENT).commitAllowingStateLoss();
}

Try to change,
#Override
public void onResume()
{
super.onResume();
if (result == null) {
// Prepare the loader. Either re-connect with an existing one,
// or start a new one.
getLoaderManager().initLoader(0, null, this);
} else {
// Restore from previous state. Perhaps through long pressed home
// button.
}
}
to
#Override
public void onResume()
{
super.onResume();
Loader loader = getLoaderManager().getLoader(0);
if ( loader != null && loader.isReset() ) {
getLoaderManager().restartLoader(0, getArguments(), this);
} else {
getLoaderManager().initLoader(0, getArguments(), this);
}
}

If you are using FragmentManager's replace fragment technique this issue will happen.
When you replace/remove the Fragment, the fragment is detached from the activity and since loaders are attached to the activity, the loaders will be recreated during orientation change.
Try using FragmentManager's hide/show technique. May be this will help you.

I've had success subclassing AsyncTaskLoader and making a few tweaks to its methods.
public class FixedAsyncTaskLoader<D> extends AsyncTaskLoader<D> {
private D result;
public FixedAsyncTaskLoader(Context context) {
super(context);
}
#Override
protected void onStartLoading() {
if (result != null) {
deliverResult(result);
} else {
forceLoad();
}
}
#Override
public void deliverResult(T data) {
result = data;
if (isStarted()) {
super.deliverResult(result);
}
}
#Override
protected void onReset() {
super.onReset();
onStopLoading();
result = null;
}
#Override
protected void onStopLoading() {
cancelLoad();
}
}