Develop Reference

Sending intent to activity from BroadcastReceiver

I have yet another question. I did some research into how to properly send an intent from a BroadcastReceiver to an activity. everyone suggests doing the following:
To construct an intent and use the context provided in the receiver to start that intent. However, I would always get an error when trying to do so saying
AndroidRuntimeException: Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
So when I googled about that error, people seemed to suggest that you want to add specific flags to the intent. But even with this flags present I am getting the same error. Any help would be appreciatd.
Intent intentMain = new Intent(context.getApplicationContext(), MainActivity.class);
intentMain.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
intentMain.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
intent.putExtra("com.hennessylabs.xxx.FROM", senderNum);
intent.putExtra("com.hennessylabs.xxx.MSG", message);
context.startActivity(intentMain);

It looks like you are trying to start MainActivity.class from your BroadcastReceiver. That is fine. Though I don't see why you have done what you did in the 2nd and 3rd lines you provided when adding flags. Why don't you just do this:
intentMain.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
So your whole code block should look like this:
Intent intentMain = new Intent(context.getApplicationContext(), MainActivity.class);
intentMain.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.putExtra("com.hennessylabs.xxx.FROM", senderNum);
intent.putExtra("com.hennessylabs.xxx.MSG", message);
context.startActivity(intentMain);

Intent intent = new Intent(context,MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(intent);
and then in manifest file
in mainactivity
launchmode= singleTask
or as per your requirements, you can use some other combinations also

startActivity() doesn't work when app is in background (In this special case)

I'm trying to bring my app from background to foreground. In onHandleIntent() of my custom IntentService class, I have:
Intent intent = new Intent();
intent.setClass(getApplicationContext(), MainActivity.class); // Also tried with "this" instead of getApplicationContext()
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setAction(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
startActivity(intent);
Now this code works at first sight but I found a scenario where it doesn't work. If you have the app opened and you put it to background via home button and execute startActivity() within ~5 second, there will be a delay before your app will come to foreground. This is a known implementation and you can find the topic discussed on stackoverflow. In this scenario, the app succeeded in coming from background to foreground.
If you repeat the same experiment above, but instead of waiting for the app to come to foreground, go browse (scroll, swipe, etc) around your phone (I was browsing around the google playstore). The result is that startActivity() will get called but the app will not come to the foreground.
I'm not asking for a solution but more of an explanation on why this is happening. Is this intended behavior?

Use the context of your class.
For instance :
Intent intent= new Intent(context, other.class)
Instead of getapplicationContext()

Use the code :
private void startMenuActivity() {
Intent i = new Intent(this, MainActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP
| Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(i);
finish();
}

the below code works for me,
val login = Intent(applicationContext, SignInActivity::class.java)
login.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK)
login.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
applicationContext.startActivity(login)

Start multilple activity from broadcastReceiver

I want to start multiple activities from my broadcast receiver. I have two classes i.e ReadContacts and CallDetails. I want to start them one by one. like first calldetails activity should be started and then next. I have tried below code and it works fine.
Intent calldetails = new Intent();
calldetails.setClassName("com.simplereader", "com.simplereader.Calldetails");
calldetails.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(calldetails);
then I tried below code to start other activity
Intent readcontacts = new Intent();
readcontacts.setClassName("com.simplereader", "com.simplereader.ReadContacts");
calldetails.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
context.startActivity(readcontacts);
But its not working and application crashes.

You must have the Intent Flag Intent.FLAG_ACTIVITY_NEW_TASK to start an Activity from outside of an Activity context so you need to add that flag to your second Intent.
I don't know if this is your only problem but if that doesn't fix it then post your logcat so we can see the error.
Intent readcontacts = new Intent();
readcontacts.setClassName("com.simplereader", "com.simplereader.ReadContacts");
calldetails.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // you need this flag
context.startActivity(readcontacts);

FLAG_ACTIVITY_MULTIPLE_TASK Do not use this flag unless you are implementing your own top-level application launcher.
From the android developer documentation for intent.
You could probably just launch both activities with the new task flag.

I think you are making mistake in this line
calldetails.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK)
If you want to start readcontacts activity it shoul be
readcontacts.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
instead of
calldetails.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
I think this is the reason.

Cannot figure out how to set FLAG_ACTIVITY_CLEAR_TOP

I would like a home button on all my actives so they can bring you to the starting point. I got some great help from stack overflow and a link to the document in http://developer.android.com/guide/topics/fundamentals/tasks-and-back-stack.html
I'm assuming I will have to set the FLAG_ACTIVITY_CLEAR_TOP flag,
the document ion has the following line
When starting an activity, you can modify the default association of an activity to its task by including flags in the intent that you deliver to startActivity(). The flags you can use to modify the default behavior are:
Ok I tried the following,
new Intent(this,TellaFortuneActivity.class, Intent.FLAG_ACTIVITY_CLEAR_TOP );
and
startActivity(i,Intent.FLAG_ACTIVITY_CLEAR_TOP);
break;
both gave me errors.
How do I do this?

Intent i=new Intent(this,TellaFortuneActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

Which is the correct way to start an Activity?

Let's say the Activity I want to start is named "OccupyThePieShop"
I was previously using this methodology to start an Activity:
Intent oTPS = new Intent();
timeIntervalConfigIntent.setClassName("com.aXX3AndSpace.KeepInTouch",
"com.aXX3AndSpace.KeepInTouch.OccupyThePieShop");
startActivity(oTPS);
...but was told that this is more the norm:
Intent oTPS = new
Intent(KeepInTouchActivity.this, OccupyThePieShop.class);
KeepInTouchActivity.this.startActivity(oTPS);
...and so I replaced my calls to startActivity() with that usage.
Now, I've come across a couple more ways which seem quite "elegant," namely:
startActivity(new Intent(getApplicationContext(), OccupyThePieShop.class));
...and:
Intent intent = new Intent(this, OccupyThePieShop.class);
startActivity(intent);
Is one way preferred over the others, and if so, why?

I think this is probably an issue of personal preference. I like startActivity(new Intent(this, OccupyThePieShop.class)); because, as you said, it is elegant.