How to remove all the activities except HomeActivity.
ex:
A(HomeActivity)->B->C->D
now call B activity again removing C & D activities. I'm sending some data from D activity to B activity through intent. I have next button if i click next button then this process will be done. If I backpress then my process will be D->C->B->A
When you're going from D->B, use intent.setFlag(Intent.FLAG_ACTIVITY_CLEAR_TOP);
It will close all of the other activities on top of it and this Intent will be delivered to the (now on top) old activity as a new Intent.
FLAG_ACTIVITY_CLEAR_TOP
Then you need to create static activity variable in both C & D activity.
Just like this
//create static variable
public static CActivity cactivity;
then initialize this variable in onCreate of Activity.
//initialization
cactivity=this;
Finish that activity where you want
// use this where you want to finish activity
CActivity.cactivity.finish();
Make sure Activity must be running in background other wise you app will crash.
what I would of suggest is a not-so-smooth solution but instead of start activities for all of those replace them with a startActivityForResult, search for the result code and if it is returned from the activity (that is for you to handle of course) then call finish with all activity in the way with the result code until you reach your home activity.
Related
So in Activity A I pass some data to activity B through an intent. Ok, everything is fine and getStringExtra returns what I expect. Then from activity B, I pass the same data to activity C. Then, when I hit the back button in the toolbar (because of getSupportActionBar().setDisplayHomeAsUpEnabled(true)), the getStringExtra in activity B is now null.
So the flow is A (passes a string)-> B(passes the same string) -> C (back button in toolbar) -> B and now the variable passes from A to B is null. How can I fix that?
Mark this a rule : Whenever you are using the toolbar back button, you should take care of specifying the launchMode of the parent activity.
In your case, what happens after you press back button in Activity C, depends on what launchMode have you specified for your activity B.
If you have't specified any launch mode, the default launch mode is standard. In this case, the parent activity (B) is popped off the stack, and a new instance of that activity is created on top of the stack to receive the intent.
If you have specified launch mode as singleTop, the parent activity is brought to the top of the stack, and receives the intent through its onNewIntent() method. That is, the previous activity is preserved.
Refer http://developer.android.com/training/implementing-navigation/ancestral.html#NavigateUp.
In your case, you want to preserve the variable, therefore you should use singleTop launchMode.
If you are extracting the data in onCreate method of Activity B then when you hit the back button in Activity C, the onCreate method of Activity B is not called again. To get more clarity on the life cycle of an Activity I really suggest you go through this developer.android.com/reference/android/app/Activity.html
Coming to your question when you start Activity B from Activity A, store the string that you sent from A to B in a global variable rather than a local one, and perform check like
public Class B extends Activity {
private String stringData;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.xml_layout);
if(getIntent().hasExtra(yourKeyName)) {
stringData = getIntent().getStringExtra(yourKeyName);
}
//Do other stuff
}
}
In your activity B, always check before getting the String -
if(getIntent().hasExtra(KEY_NAME))
String s = getIntent().getStringExtra(KEY_NAME);
Reason being that when you press the back button then Activity B is not launched with the same intent that you create in Activity A. Hence the extras are not present.
You should be string the string extra as a global variable and always use a hasExtra check.
I think it is different processes.
The first one, when you start activity B from activity A, you pass
the data from activity A to activity B. It is obvious, so the data
will be present.
The second one, then you start activity C from activity B, because of
activity B is not on the foreground, then your data will be erased.
You can persist your data on activity B by many ways.
One of them you can implement a static global variable.
Second way, you can save your variables on activity B by saving the
data onSaveInstanceState and retrieve from onRestoreInstanceState or
onCreate
Third way you can listen onActivityResult on activity B from activity
C. When you starting activity C, you must use startActivityOnResult
and passing the data that you want to pass back on activity B. After
you finish your activity C, you must return the data that originally
from activity B.
And so on...
But the better way to achieve that is the second way, use bundle onSaveInstanceState and retrieve the bundle data when onCreate.
How can I restart An Activity on click?
For exemple: I have got in my AndroidManifest.xml 2 activities the activity A and B and they start when application starts...
But what I want is when I click in a button that is on Activity A it must restart activity B.
when you are in activity A, and proceeding to activity B, then your activity B automatically starts/re-starts
Why do you need to start both Activities on starting your app? When you say "restart", do you actually need to stop Activity B and start Activity B again? Or do you just want to show it? To start an Activity from another Activity, you could call something like this:
startActivity(new (Intent(this, ActivityB.class)));
The Android documentation gives plenty of detail. However, I think you should consider why you are starting two activities at once, and whether you might want to use a Service instead (not knowing any details of your app, I can't say).
Intent intent = new Intent(CurrentActivity.this, ActivityToLaunch.class);
startActivity(intent);
call above piece of code on onClick of view method.
What is the difference between Intent.FLAG_ACTIVITY_CLEAR_TOP and finish() in Android?
The differerence between these two are as follows:
1.finish() you can use to end the activity in which you are right now present and also it will end one activity at one time.
2.In case of FLAG_ACTIVITY_CLEAR_TOP,It will end all the activities those are on top of the current activities inside the stack.There may be more than one activity.
suppose you are starting activities one after another in the order
A-->B-->C-->D,ie activity B started from activity A,activity C started from activity B and so on.
Now calling startactivity(A) from activity D with intent flag FLAG_ACTIVITY_CLEAR_TOP finishes all activities in between (here B and C) and starts A.
calling Finish() from your activity closes current activity
finish() android uses to end the activity by calling it in program.
(Note, you can also use onDestroy()).
FLAG_ACTIVITY_CLEAR_TOP clears all the activities that are top of the current activities inside the Activity stack.
I have an Android application that contains two Activities.
Activity A has a button that launches Activity B using Context.startActivity(Intent intent).
There is also a Notification that opens Activity in the same way.
If I start B from this notification and press back button - it just closes B and does not shows A like I go there with normal case.
Is it possible to force B to bo back to A if started from notification without history stack ?
Solution
As stefan and Paul Lammertsma mentioned, the best way is to start A from notification and in A create new intent with B - but not in onCreate() !
I dig this a bit and found that if I set in AndroidManifest a new property for A activity:
android:launchMode="singleTask"
there will be in A activity called
onNewIntent(Intent intent)
And there we should checl if Intent containst extra value passed from notification - and if so, then we call new B intent.
Thank you both and good luck with it for next devs ;-)
I would suggest having the notification call Activity A (instead of B directly) with some flag in its extras bundle. In A's onCreate(), check for the flag, and immediately launch Activity B. This will ensure that pressing back on B will return to A.
An easy way to achieve this would be to actually start Activity A from your Notification with a flag to call Activity B instantly.
So you just have to put an extra to your intent you are starting in your Notification and you have to check in Activity A if this extra exists and if it exists then you start Activity B.
Update: another way, but in my opinion not so good, would be to override the onPause() method of your Activity B and call Activity A there.
Maybe not the prettiest solution, but nevertheless a quick one;
add a boolean extra to the intent launching B, "launchedFromNotification" or something like that.
In activity Bs onCreate() you store that boolean value for later use.
In activity Bs onBackPressed() you can check the value of your boolean and if true, launch activity A before calling finish();
A prettier solution may be to launch activity A from the notification, with an extra telling it to directly launch activity B.
In our requirement, we need to refresh A activity after B activity finish.
but B activity is set as singletask.
Is there any flag or another API can fulfill this requirement?
thank you.
AFAIK, the only way to achieve the thing you want - using broadcasting: when B has been finished - send broadcast and in A catch it.
btw, is it so necessary to use singletask?
If you want to set some result to activity A from Activity 2 then you have two options
1) If you have one activity already in activity stack then you have two options
1=> Use startActivityFroResult() and set result back to calling activity
2=> Make fields in activity A as public static and assign values from activityB and onResume() of ActivityA refresh view of ActivityA
2) If you have not ActivityA in activity stack then just pass the necessary values with the intent and from ActivityA onCreate() method fetch all values from intent and load view