Develop Reference

How can I prevent my app from showing specific apps on startActivity()

When a user clicks a button in my app, it's supposed to launch an SMS app. To to this, I simply fired an intent.
Intent intent = new Intent(Intent.ACTION_VIEW, Uri.fromParts("sms", "+234000000000", null));
intent.putExtra("sms_body", "Hello!"));
if (intent.resolveActivity(getActivity().getPackageManager()) != null) startActivity(intent);
This works perfectly fine! The only problem is that Facebook Messenger is among the list of apps that show up and I don't want that.
How can I filter this list and remove specific apps like Messenger?

Yes, you can restrict your app to open just android default messaging app.
Uri uri = Uri.parse("sms:+444498494984");
Intent intent = new Intent(Intent.ACTION_SENDTO, uri);
//android sms app package name
intent.setPackage("com.google.android.apps.messaging");
intent.putExtra("sms_body", "message to send");
if (intent.resolveActivity(getPackageManager()) != null)
{
startActivity(intent);
}

It is trying to give the user a choice on their favourite SMS app, Don't forget that Facebook Messenger can also manage SMS now that is why it is showing up as a choice. In my experience, Unless the user selects 'always' it can't be avoided. Imagine if the user has other apps to manage SMS we can't force them to use our preferred messaging app.

How to solve android email intent problem?

I am having a problem with android email intent.....i need to open email app so that the user can provide feedback for my app.It doesn't open when i use this..throws an ActivityNotFoundException .....i am using my phone ,not an emulator and my phone has email and gmail apps in it.
Help me solve??
Here is my code:
Intent intent= new Intent(Intent.ACTION_SENDTO);
intent.setData(Uri.parse("mailto:"));
intent.setType("text/plain");
String[] mail={"someone#gmail.com"};
intent.putExtra(Intent.EXTRA_SUBJECT,"");
intent.putExtra(Intent.EXTRA_TEXT,"");
intent.putExtra(Intent.EXTRA_EMAIL,mail);
startActivity(intent);
Any and all comments are appreciated :)

For your case, what ActivityNotFoundException most likely means that in your phone you don't have any default email app email application installed on your device like Gmail, so when you launch the Intent you receive this error.
You can try to handle that exception like this:
try {
startActivity(Intent.createChooser(i, "Send mail"));
} catch (android.content.ActivityNotFoundException ex) {
Toast.makeText(Activity.this, "no email app",Toast.LENGTH_SHORT).show();
}

From the android docs, An intent allows you to start an activity in another app by describing a simple action you'd like to perform (such as "view a map" or "take a picture") in an Intent object. This type of intent is called an implicit intent because it does not specify the app component to start, but instead specifies an action and provides some data with which to perform the action.
When you call startActivity() or startActivityForResult() and pass it an implicit intent, the system resolves the intent to an app that can handle the intent and starts its corresponding Activity. If there's more than one app that can handle the intent, the system presents the user with a dialog to pick which app to use.`
So, in your case, the system couldn't find an app to resolve the intent to as #Tamir mentioned.
For more information , look into this Stack Overflow post: Send Email Intent

it works for me :
String[] recipients;
Intent intent = new Intent(Intent.ACTION_SEND);
recipients = new String[]{"someone#gmail.com"};
intent.putExtra(Intent.EXTRA_EMAIL, recipients);
intent.setType("text/html");
intent.setPackage("com.google.android.gm");
try {
activity.startActivity(Intent.createChooser(intent, "Send"));
}
catch (android.content.ActivityNotFoundException ex) {
Toast.makeText(Activity.this, "no email app",Toast.LENGTH_SHORT).show();
}

Android: Don't open app after performing notification on-click action

The main part of my app is a service that displays a notification. The GUI of the app is only used to be able to change some settings. When I click on that notification, some data should be send in the background without opening the app. To do that, I created an invisible activity.
When I open the app (the configuration part) and exit it with the back button, everything works as intended; when clicking on the notification the data is send without opening the app.
When I exit the app with the home button, every time I click the notification the app opens again.
This is my notification and the Intent to call the data activity:
PendingIntent toggleLightsIntent =
PendingIntent.getActivity(
this,
0,
new Intent(this, HyperionToggleSwitchActivity.class),
PendingIntent.FLAG_NO_CREATE);
Notification notification = new Notification.Builder(this)
.setSmallIcon(R.drawable.ic_launcher)
.setContentTitle("HyperionSwitch")
.setContentText("Switch lights")
.setContentIntent(toggleLightsIntent)
.build();
And this is the part where I send the data:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
sendJson(blue);
finish();
}
What do I have to change so the app won't open when clicking the notification?
It's my first app and took me quite a while to get what I have so far...

As per earlier comment:
You could change your hidden activity into a Service (which generally doesn't have any ui), or leverage the service that manages the notification, and have the PendingIntent sent directly to that service using PendingIntent.getService() .

Try this code^
Intent intent = new Intent(this, MainActivity.class);
intent.putExtra(MainActivity.FILE_NAME, "somefile");
PendingIntent pIntent = PendingIntent.getActivity(this, 0, intent, 0);

How do i redirect the user to Data Usage settings in android?

Like if i want to redirect the user to Location service i have to use
Intent intent = new Intent(
Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(intent);
Now what shoulb the ACTION_ to let the user go to the data usage settings where he can enable the Mobile Data Traffic?

Are you sure you aren't looking for:
final Intent dataUsage = new Intent(Intent.ACTION_MAIN);
dataUsage.setClassName("com.android.settings",
"com.android.settings.Settings$DataUsageSummaryActivity");
startActivity(dataUsage);
Your title suggests that's what you want, but your comment suggests you wanted the network operator settings.

Restart application when i click a button

I need that my application restarts when click a button, for more info I need simulate thant I push back key and open application again.
I supose that i can close application with finish(); but how can i do to launch onCrete() again?
is there other way to do this?
thanks

Call your Activity using an Intent. It will launch the activity again.
Intent intent = new Intent(MyActivity.this, MyActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); //this will always start your activity as a new task
startActivity(intent);
You can also add, android:launchMode="singleTask" inside your Manifest so that only one instance of your activity will be maintained at any time.
Same thing here. :)

Intent i = getBaseContext().getPackageManager()
.getLaunchIntentForPackage( getBaseContext().getPackageName() );
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);

To restart your application you can use alarm manager to make your activity open after you exit the app.
AlarmManager alm = (AlarmManager) getActivity().getSystemService(Context.ALARM_SERVICE);
alm.set(AlarmManager.RTC, System.currentTimeMillis() + 1000, PendingIntent.getActivity(context, 0, new Intent(context, MainActivity.class), 0));
android.os.Process.sendSignal(android.os.Process.myPid(), android.os.Process.SIGNAL_KILL);