Develop Reference

How to destroy the a media player from a fragment?

I am a solo developer so I am still learning. I am trying to use Fragments for a game's menu. In the menu there is an option to preview and set background music. So in the MusicFragment I have this code:
public class MusicFragment extends Fragment {
Music music = new Music();
// more code //
private void previewSong() {
music.playSong(getActivity(), "Song_1", milliseconds)
}
private void stopSong() {
music.stopPlayer();
}
}
I have a separate class - "Music" for the music, the code is like so:
public class Music extends Activity {
MediaPlayer player;
public void playSong(Context context, String songName, int milliseconds) {
if(player == null) {
player = MediaPlayer.create(context, R.raw.song1);
player.seekTo(milliseconds);
player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer mp) {
}
});
}
player.start();
}
public void stopPlayer() {
if(player !=null) {
player.stop();
player.reset();
player.release();
player = null;
}
}
public String playerStatus() {
if(player == null) {
return "player is null";
} else {
return "player is NOT null";
}
}
}
I can start and stop the player from the fragment with no problems. What I am trying to solve for is the occasion where the user previews the music and then closes/minimizes the app - without turning the music off (stopPlayer()) in the MusicFragment (the music still playing).
In that case the app closes but the music is still ongoing. My understanding is that fragments (in this case MusicFragment) do not have onPause(). The Main_Activity does have onPause - but when I read the MediaPlayer's status via the Main_Activity's onPause() it displays the playerStatus as "NULL" even though song1 is still playing on the device while the app is closed.
I've tried to exclude the additional Music class and just create the MediaPlayer in the MusicFragment but the result is the same. Obviously if the Fragment had an OnPause I would call the stopSong() method from there. I think I'm not understanding a fundamental concept. Any assist would be greatly appreciated.

You can make the stopSong() method in MusicFragment public. Create an instance of MusicFragment in your activity and then call the stopSong() method.
public class MusicFragment extends Fragment {
Music music = new Music();
// more code //
private void previewSong() {
music.playSong(getActivity(), "Song_1", milliseconds)
}
public void stopSong() {
music.stopPlayer();
}
}
In your activity:
public class MainActivity extends appCompatActivity{
MusicFragment musicFragment;
...
#Override
protected void onPause() {
super.onStop();
musicFragment=new MusicFragment();
musicFragment.stopSong();
}
}

show app lock pattern dialog when unlocking the phone

I have MainActivity and on its onResume method I call pattern lock to create and confirm user identity. User visits and leave this MainActivity back and forth while active on the app as well as when phone is in sleep mode and user unlocks it. These both scenarios will call onRestart, onStart and onResume methods, but I only want to revoke the pattern in unlock scenario.
handlePattern() method needs a proper distinguishing to be called.
How to distinguish this when I call the handlePattern method ?
MainActivity.class
onCreate(){}
onResume(){
//help needed to know that user is just visiting activity in app back and forth
or came back after unlocking the screen.
if(isPatternCallRequired){
handlePattern()
}
}

In your onStop() method call you can check if the player is in sleep mode and cache the boolean.
PowerManager pm = (PowerManager)
_context.getSystemService(Context.POWER_SERVICE);
boolean isInSleepMode = !pm.isScreenOn();
Check for the build version
if( Build.VERSION.SDK_INT >= 20)
// use isInteractive()
else
// use isScreenOn()
in onRestart which will get called when you resume from sleep - based on the cached value you can show the pattern to unlock.
You may need to reset the cached value once you are done using it.
onResume may not be a right API for the call as it will be called even when your activity loads.
Edited answer based on your comment

You can try ActivityLifecycleCallbacks too like this,
First, Register your Application in your Application class.
public class StackApp extends Application {
private static final String TAG = StackApp.class.getSimpleName();
public static final String INTENT_ACTION_APP_STATE_CHANGE = "intent_action_app_state_change";
public static final String INTENT_DATA_IS_IN_BACKGROUND = "intent_data_is_in_background";
private static int mNumRunningActivities = 0;
private static AtomicBoolean mIsAppInForeground = new AtomicBoolean();
#Override
public void onCreate() {
super.onCreate();
if (Build.VERSION.SDK_INT >= 14) {
// registerActivityLifecycleCallbacks is supported only from the SDK version 14.
registerActivityLifecycleCallbacks(new Application.ActivityLifecycleCallbacks() {
#Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
}
#Override
public void onActivityStarted(Activity activity) {
mNumRunningActivities++;
if (mNumRunningActivities == 1) {
notifyAppState(false);
Log.i(TAG, "APP IN FOREGROUND");
}
}
#Override
public void onActivityResumed(Activity activity) {
}
#Override
public void onActivityPaused(Activity activity) {
}
#Override
public void onActivityStopped(Activity activity) {
mNumRunningActivities--;
if (mNumRunningActivities == 0) {
notifyAppState(true);
}
}
#Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
#Override
public void onActivityDestroyed(Activity activity) {
}
});
}
}
/**
* To notify App state whether its in ForeGround or in Background
*
* #param isInBackground
*/
private void notifyAppState(boolean isInBackground) {
if (isInBackground) {
mIsAppInForeground.set(false);
} else {
mIsAppInForeground.set(true);
}
sendAppStateChangeBroadcast(isInBackground);
}
public static boolean isInForeground() {
return mIsAppInForeground.get();
}
private void sendAppStateChangeBroadcast(boolean isInBackground) {
Log.i(TAG, "sendAppStateChangeBroadcast - isInBackground : " + isInBackground);
Intent intent = new Intent();
intent.setAction(INTENT_ACTION_APP_STATE_CHANGE);
intent.putExtra(INTENT_DATA_IS_IN_BACKGROUND, isInBackground);
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}
}
And register the broadcast and listen whether the App is going background or foreground like this Sample Activity example
public class SampleMyActivity extends AppCompatActivity {
private OnAppStateReceiver mAppStateReceiver;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sample_my);
mAppStateReceiver = new OnAppStateReceiver();
IntentFilter filter = new IntentFilter(StackApp.INTENT_ACTION_APP_STATE_CHANGE);
LocalBroadcastManager.getInstance(this).registerReceiver(mAppStateReceiver, filter);
}
#Override
protected void onDestroy() {
super.onDestroy();
if (mAppStateReceiver != null) {
LocalBroadcastManager.getInstance(this).unregisterReceiver(mAppStateReceiver);
}
}
private class OnAppStateReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (!TextUtils.isEmpty(action) && StackApp.INTENT_ACTION_APP_STATE_CHANGE.equalsIgnoreCase(action)) {
boolean isGoingBackground = intent.getBooleanExtra(StackApp.INTENT_DATA_IS_IN_BACKGROUND, false);
if (isGoingBackground) {
//Your app is not vissible to the use
} else {
// App is visible to the user.
}
}
}
}
}
Note: If you want to listen in Multiple Activity you can create a base
class and add the listener there and you can do the operation, In that
case you can reduce a lot of code.

Android Java: Update seekbar to show progress as audio file plays

This is my first Android/Java app. I am using the first answer here to try to initiate a repeating task, updating a seekbar ("timeSlider") to show progress as an audio file plays. Here is my code (eliminating a few irrelevant lines):
private int timeSliderInterval = 1000; // 1 second
private Handler timeSliderHandler;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play);
Intent intent = getIntent();
Runnable doUpdateTimeSlider = new Runnable() {
#Override
public void run() {
timeSliderHandler.postDelayed(doUpdateTimeSlider, timeSliderInterval);
updateTimeSlider();
}
};
void startUpdateTimeSlider() {
doUpdateTimeSlider.run();
}
void stopUpdateTimeSlider() {
timeSliderHandler.removeCallbacks(doUpdateTimeSlider);
}
final SeekBar timeSlider = (SeekBar) findViewById(R.id.timeSlider);
if (timeSlider != null) {
timeSliderHandler = new Handler();
startUpdateTimeSlider();
}
#Override
public void onDestroy() {
super.onDestroy();
stopUpdateTimeSlider();
}
The project does not display in the emulator. Tooltips show these errors:
In addition, the startUpdateTimeSlider and stopUpdateTimeSlider functions are showing this error in tooltips:
Also, in the Run window, I'm getting:
emulator: emulator window was out of view and was recentered
emulator: ERROR: _factory_client_recv: Unknown camera factory query
name in ' '
Any help will be greatly appreciated!

First issue is self explained, you need to add final modifier.
final Runnable doUpdateTimeSlider = ...
Second one - move startUpdateTimerSlider() method, now its inside onCreate() method
Looks like you missed }:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play);
Intent intent = getIntent();
Runnable doUpdateTimeSlider = new Runnable() {
#Override
public void run() {
timeSliderHandler.postDelayed(doUpdateTimeSlider, timeSliderInterval);
updateTimeSlider();
}
};
}//<--------HERE
void startUpdateTimeSlider() {
doUpdateTimeSlider.run();
}

While using the IntentIntegrator from the ZXing library, can I add a flash button to the barcode scanner via the Intent?

I am scanning barcodes and QR codes from an Android app via Intent using the ZXing Library and its port of the Android Application. I added the following two lines in my Gradle dependencies to use the android-integration code without modification:
compile 'com.journeyapps:zxing-android-embedded:3.2.0#aar'
compile 'com.google.zxing:core:3.2.1'
And I am using IntentIntegrator in my Activity to scan a barcode in the onCreate() like this:
integrator = new IntentIntegrator(this);
integrator.setOrientationLocked(false);
integrator.setPrompt(getString(R.string.scanner_text)); // Set the text of the scanner
integrator.setCameraId(0); // Use a specific camera of the device
integrator.setBeepEnabled(true); // Enable beep in the scanner
integrator.setBarcodeImageEnabled(false); // Do not fetch image from the camera
integrator.initiateScan();
Everything works and I get correct scanned result, but I want a flash button in the lower right corner of the scanner like this:
I can already control the flash using the volume up and down keys because I override the CaptureActivity.
Is a flash button like the one above already there in the barcode scanner which can switch between AUTO, ON and OFF mode? If there is, can I use the addExtra() method of the IntentIntegrator to activate it? Or is the only way to implement this would be to modify the entire code according to my needs?

I had overlooked this page on Embedding BarcodeView and these sample activities which show how to customise the Barcode Scanner according to your needs. The example activity that helped me was CustomScannerActivity.
There isn't a option in the IntentIntegrator class to implement a flash button natively. Instead I should make a custom layout for the Barcode Scanner, use it in a custom activity and call this activity from the IntentIntegrator.
I have two activities. One is the ScannerActivity and other one is the CallingActivity. A mistake that confused me for a while was that I created an instance of IntentIntegrator in the onCreate() method of ScannerActivity. It should be in the CallingActivity.
In the example given a Button is used and the text of the Button is changed according to the flash. I created a new Android Layout called activity_custom_scanner where I replaced the Button with a ToggleButton and used images for the button instead to get my desired Flash On/Off Button.
So my ScannerActivity looks like this:
public class CustomScannerActivity extends Activity implements
CompoundBarcodeView.TorchListener {
private static final int BarCodeScannerViewControllerUserCanceledErrorCode = 99991;
private static final String TAG = CustomScannerActivity.class.getSimpleName();
private CaptureManager capture;
private CompoundBarcodeView barcodeScannerView;
private ToggleButton switchFlashlightButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_custom_scanner);
barcodeScannerView = (CompoundBarcodeView)findViewById(R.id.zxing_barcode_scanner);
barcodeScannerView.setTorchListener(this);
switchFlashlightButton = (ToggleButton)findViewById(R.id.switch_flashlight);
switchFlashlightButton.setText(null);
switchFlashlightButton.setTextOn(null);
switchFlashlightButton.setTextOff(null);
// if the device does not have flashlight in its camera,
// then remove the switch flashlight button...
if (!hasFlash()) {
switchFlashlightButton.setVisibility(View.GONE);
}
switchFlashlightButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// Save the state here
if (isChecked) {
barcodeScannerView.setTorchOn();
} else {
barcodeScannerView.setTorchOff();
}
}
});
capture = new CaptureManager(this, barcodeScannerView);
capture.initializeFromIntent(getIntent(), savedInstanceState);
capture.decode();
}
#Override
protected void onResume() {
super.onResume();
capture.onResume();
}
#Override
protected void onPause() {
super.onPause();
capture.onPause();
}
#Override
protected void onDestroy() {
super.onDestroy();
capture.onDestroy();
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
capture.onSaveInstanceState(outState);
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
return barcodeScannerView.onKeyDown(keyCode, event) || super.onKeyDown(keyCode, event);
}
/**
* Check if the device's camera has a Flashlight.
* #return true if there is Flashlight, otherwise false.
*/
private boolean hasFlash() {
return getApplicationContext().getPackageManager()
.hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
}
#Override
public void onTorchOn() {
// necessary override..
}
#Override
public void onTorchOff() {
// necessary override..
}
}
And the CallingActivity looks like this:
public class CallingActivity extends Activity {
private static final String TAG = CallingActivity.class.getSimpleName();
private static final int BarCodeScannerViewControllerUserCanceledErrorCode = 99991;
String uuid;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
uuid = getIntent().getStringExtra("uuid");
new IntentIntegrator(this).setOrientationLocked(false).setCaptureActivity(CustomScannerActivity.class).initiateScan();
}
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
IntentResult scanResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, intent);
if (resultCode == RESULT_OK) {
if (scanResult != null) {
// handle scan result
Log.i(TAG, "Text from Barcode Scanner: " + scanResult.getContents());
getIntent().putExtra("data", scanResult.getContents());
getIntent().putExtra("uuid", uuid);
}
}
else if (resultCode == RESULT_CANCELED) {
getIntent().putExtra("error", "User canceled");
getIntent().putExtra("error_code", BarCodeScannerViewControllerUserCanceledErrorCode);
}
else
{
getIntent().putExtra("error", getString(R.string.scanner_error));
getIntent().putExtra("error_code", BarCodeScannerViewControllerUserCanceledErrorCode);
}
setResult(resultCode, this.getIntent());
this.finish();
}
}
I am not sure if it's the perfect way, but that's how I did it.
Hope it helps someone!

There is a setTorchOn method in CompoundBarcodeView so you can check that method out and try to implement it for your needs. Hope it helps.

This question is probably too old, but you can use the Volume buttons to turn on/off the torch while scanning.

Show ProgressDialog during a network call until it's FINISHED

I am very frustrated as I've been trying to implement a super simple loading wheel while waiting on a network call. I have searched and read dozens of SO questions and I just feel like I must be missing something, unless nobody really does what I'm trying to do. I have tried going down the AsyncTask route, but that's not what I want.
Let me also say that right now my app works perfectly, it's just that the transition from screen to screen appears to hang as it waits on the network. I just want a loading wheel so that in the 1-2 seconds the user knows the app is working and didn't freeze.
Here's what my current network call looks like:
private static String sendDataToServer(String arg1, String arg2)
{
Thread dbThread = new Thread()
{
public void run()
{
// do the call that takes a long time
}
};
dbThread.start();
try {
// I do this so that my program doesn't continue until
// the network call is done and I have received the information
// I need to render my next screen
dbThread.join();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
Now, why can't I just add the ProgressDialog like this? If I do this, the progressDialog never appears.
private static String sendDataToServer(String arg1, String arg2)
{
final ProgressDialog progress = new ProgressDialog(BaseActivity.getInstance());
progress.setIndeterminate(true);
progress.setMessage("Loading...");
progress.show();
Thread dbThread = new Thread()
{
public void run()
{
// do the call that takes a long time
}
};
dbThread.start();
try {
dbThread.join();
progress.dismiss();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
I think I'm stuck because the network call needs to be on a separate thread from the UI thread, yet I don't want to continue in my application because I need the results of that call to continue. But if I do thread.join() I hold up everything. I thought I needed AsyncTask but that went downhill quickly. Here's my question on that if you're curious.
Android's AsyncTask: multiple params, returning values, waiting
How the heck to I just show a loading dialog while this call happens without proceeding through the rest of my application?
EDIT
Here's my AsyncTask attempt.
private class PostToFile extends AsyncTask<PostToFile, Void, Void>{
private String functionName;
private ArrayList<NameValuePair> postKeyValuePairs;
private String result = "";
public PostToFile(String function, ArrayList<NameValuePair> keyValuePairs){
functionName= function;
postKeyValuePairs = keyValuePairs;
}
#Override
protected void onPreExecute() {
progressDialog = ProgressDialog.show(BaseActivity.getInstance(), "Loading", "Please wait...", true, false);
}
#Override
protected Void doInBackground(PostToFile... params) {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair(FUNCTION_KEYWORD, functionName));
for (int i = 0; i < postKeyValuePairs.size(); i++) {
nameValuePairs.add(postKeyValuePairs.get(i));
}
try{
// ***do the POST magic.***
result = response.toString();
}
catch (Exception e){
// clean up my mess
}
return null;
}
private String getResult(){
return result; // can I use this somehow???
}
#Override
protected void onPostExecute(Void result) {
progressDialog.dismiss();
}
}
And when I use it:
new PostToPHP(FUNCTION_NAME, postPairings){
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try
{
if (result != null && !result.startsWith("null"))
{
JSONArray jArray = new JSONArray(result);
parseData(jArray);
}
}
catch (JSONException e)
{
Log.e(Constants.LOG_TAG, e.toString());
}
};
}.execute()
The problem is, I have a couple of these calls back to back, and they're each dependent on each other. So the first one starts, and the second one starts immediately after the first one starts, but before the first one is finished. So I get erroneous behavior. How can I start the second call only after the first is completely done?

Maybe this will work, I haven't tested, but you can try:
public class MyTask extends AsyncTask<String, Void, String> {
private int flag;
public MyTask(int flag) {
this.flag = flag;
}
#Override
protected String doInBackground(String... params) {
switch (flag) {
case 1:
return doNetworking1();
break;
case 2:
return doNetworking2();
break;
case 3:
return doNetworking3();
break;
default:
return doNetworking1();
}
}
#Override
protected void onPreExecute() {
//show progress dialog
}
#Override
protected void onPostExecute(String s) {
//hide progress dialog
switch (flag) {
case 1: //do something with result
new MyTask(2).execute();
break;
case 2: //do other stuff
new MyTask(3).execute();
break;
case 3: //do event more stuff
break;
default:
//do something
}
}
}
and usage:
new MyTask(1).execute();

In cases of network connections I would use IntentService instead of AsyncTask.
For example create IntentServices for network connection:
public class NetworkCallIntentService extends IntentService {
public static final String BROADCAST_ACTION = "com.yourpackage:NETWORK_CALL_BROADCAST";
public static final String RESULT = "com.yourpackage:NETWORK_CALL_RESULT";
public NetworkCallIntentService() {
super(NetworkCallIntentService.class.getSimpleName());
}
#Override
protected void onHandleIntent(Intent intent) {
// get data from intent if needed
// do the call that takes long time
// send broadcast when done
Intent intent = new Intent(BROADCAST_ACTION);
intent.putExtra(RESULT, "some_result");//and more results
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}
}
Next, start that service from activity, show progress dialog and move code responsible for showing next screen to BroadcastReceiver#onReceive() method:
public class SomeActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//start service
Intent serviceIntent = new Intent(this, NetworkCallIntentService.class);
//put extras into intent if needed
//serviceIntent.putExtra("some_key", "some_string_value");
startService(serviceIntent);
//here just show progress bar/progress dialog
}
#Override
protected void onResume() {
super.onResume();
LocalBroadcastManager.getInstance(getApplicationContext()).registerReceiver(mNetworkCallReceiver,
new IntentFilter(NetworkCallIntentService.BROADCAST_ACTION));
}
#Override
protected void onPause() {
super.onPause();
LocalBroadcastManager.getInstance(getApplicationContext()).unregisterReceiver(mNetworkCallReceiver);
}
private BroadcastReceiver mNetworkCallReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//hide progress bar/progress dialog
//here get results from intent extras
String result = intent.getStringExtra(NetworkCallIntentService.RESULT);
//process results and continue program(go to next screen, show error message etc.)
}
}
}
Declare service in manifest file:
<service
android:name="com.yourpackage.DownloadSvtValuesIntentService"
android:exported="false" >
</service>