How to switch activities in Android? - android

Now I have 3 activities, activity1, activity2 and activity3. I open the activities in order and never close any of them. So now I am in activity3, but I want to go back to activity1 and it must be the one which I opened. Is there any way to do that?

start activity 1 from 3 with FLAG_ACTIVITY_CLEAR_TOP flag:
Intent intent = new Intent ( this, Activity1.class );
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);

according to developer doc, you should use FLAG_ACTIVITY_CLEAR_TOP into the intent you want to start.
FLAG_ACTIVITY_CLEAR_TOP :
If set, and the activity being launched is already running in the
current task, then instead of launching a new instance of that
activity, all of the other activities on top of it will be closed and
this Intent will be delivered to the (now on top) old activity as a
new Intent.
use addFlags before start back activity1.

Related

How to navigate to a particular activity?

I am having 3 activities. From the third activity, I need to come back to the 1st activity when a GUI button is clicked. I know I can click the "physical" back button 2 times to make this but that is not an option.
So, is there any way I can display the 1st activity, without creating a new instance? I can pass the 1st activity's instance to the third activity, no issue with that.
Use the FLAG_ACTIVITY_CLEAR_TOP in your intent.
From the documentation:
For example, consider a task consisting of the activities: A, B, C, D. If D calls startActivity() with an Intent that resolves to the component of activity B, then C and D will be finished and B receive the given Intent, resulting in the stack now being: A, B.
To use:
Intent intent = new Intent(getBaseContext(), FirstActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
Intent intent = new Intent(src_ctxt, dest.class);
intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);
src_ctxt.startActivity(intent);
This should do it
I think you need to make your activity B singleInstance that if it's already create you don't want to create again, that is launch mode of the activity can be defined in manifest android:launchMode that defines how the activity will be instanciated.
in your case use android:launchMode="singleInstance"
or
You can use flag Intent.FLAG_ACTIVITY_NEW_TASK. If the activity is already running it will bring that to front instead of creating new activity.

Android:Delete a activity in backstack

I have got 4 activity let it be A->B->C->D.In every A,B,C activity user need to enter data all data will sent to server in C activity if the user data is correct he will move on to D activity and all the activity A,B,C removed from stack.If the data is in correct i need give the user to reenter data i.e is on back press it has to move C->B->A.My question is How to remove A,B,C activity when user enter D activity.
Use FLAG_ACTIVITY_CLEAR_TOP this shall solve your problem
From the Android documentation:
If set, and the activity being launched is already running in the
current task, then instead of launching a new instance of that
activity, all of the other activities on top of it will be closed and
this Intent will be delivered to the (now on top) old activity as a
new Intent.
For example, consider a task consisting of the activities: A, B, C, D.
If D calls startActivity() with an Intent that resolves to the
component of activity B, then C and D will be finished and B receive
the given Intent, resulting in the stack now being: A, B.
Use it like
Intent intent = new Intent(getApplicationContext(),
yourActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
and also, take a look at this question:
Activity with Flag FLAG_ACTIVITY_CLEAR_TOP (android)
Edit : I thought you want to move to your home activity from D and want to remove all activities from stack
Your stack would be like homeactivity , A , B , C , D
so i gave you this solution as this shall remove all activities in stack on top of your home activity.
If you want to clear the the stack while going to D, for that you can use FLAG_ACTIVITY_TASK_ON_HOME or FLAG_ACTIVITY_CLEAR_TASK
But both of these for api level 11.
The correct answer interesting for me also, but I can offer a solution:
For example you start activity A from O: O->A->B->C->D.
On activity O you can put in android manifest android:launchMode="singleTop"
Then, when data are ok, you can start activity O with flag "FLAG_ACTIVITY_CLEAR_TOP" - it remove from stack A,B,C and will be called method onNewIntent (Intent intent) http://developer.android.com/reference/android/app/Activity.html#onNewIntent(android.content.Intent) in O, where you can start activity D.
You can start activities with startActivityForResult, and call setResult from for example activity D, in C activity you can listen activity result, and related of this result finish activity or not, or call setResalt from C activity ...
When you want to move D activity there you need to check your
conditions and if your condition is satisfied then you need to enter
into your Next activity(i.e., D) .In that case you need to use the
following code..
Intent intent = new Intent(this,D.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
Suppose In on backpress you need to use finish(). to move back i.e., C
-> B -> A.
Try this piece of code with some modifications:
Intent intent = new Intent(this, D.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // To clean up all activities
startActivity(intent);
Try looking for Activity's public method startActivity(Intent i) and finish() here
In usage wise, it should look like this.
Intent i = new Intent(MainActivity.this, MainActivity.class);
startActivity(i);
finish();
Hope this helps :D

finish() activity twice in android?

Okay say your using a app, and you opened a new activity and then opened another, you can end the activity your on by using finish(); and your back one activity, but how can you go back two activities, all the way back to the first one? I know you could use:
Intent savedGameIntent = new Intent(v.getContext(), firstclass.class);
v.getContext().startActivity(savedGameIntent);
But is that the best way to do it?
Use the flag Intent.FLAG_ACTIVITY_CLEAR_TOP.
Intent intent = new Intent(this,A.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
From the documentation:
If set, and the activity being launched is already running in the current task, then instead of launching a new instance of that activity, all of the other activities on top of it will be closed and this Intent will be delivered to the (now on top) old activity as a new Intent.
So effectively, if you have A -> B -> C, and you intent to A with that flag set, B and C will close.
I believe that will start a new activity, not back up to the original one. It sounds like you want to finish the last and middle activities. If you start the last activity with startActivityForResult, you can then override onActivityResult in the middle activity, and call finish() from there.

How to close all child activities from parent in android [duplicate]

I'm new to android. Actually one handler is running in Home Activity A for every 30 sec to check the net connection.
If I'm went to activity C by A->B->C, If there in no net connection at that time, then i want to close Activity B and C, then want to show message box in Activity A.
But My problem is My handler is running for every 30 sec in Home Activity A. But If i was in Activity C or some other Activity how to find which activity is my Application currently focussed now. Then i want to finish those child activities and want to show Home Activity A I have some 9 child activities in Activity B.
I heard about using "FLAG_ACTIVITY_CLEAR_TOP" . I used the code as follows in the handler in Home activity A itself. But got error.
Intent intent = new Intent( ctx, Homepage.class );
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP |
Intent.FLAG_ACTIVITY_CLEAR_TOP);
ctx.startActivity( intent );
Here Homepage.class is my Home Activity A and i set that activity in manifest file as
android:launchMode="singleTop"
Please help!
You can start Activity A and close all other activities.
You have to create new intent and add flag FLAG_ACTIVITY_CLEAR_TOP
Intent activityA = new Intent(context, ActivityA.class);
activityA.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
context.StartActivity(activityA);
this will close all activities that are in the stack and are at the top of activity A
When calling Acitivity C, call finish in activity B , when calling Activity A from C , call finish() in activity C !
You can use, According to me two ways,
If you start an activity using startActivityForResult, then you can call finish() in this new Activity when you're done with it and it will return control to the activity that started it.
OR otherwise, May be I am wrong,
Call finish inside onStop 'override method'.
make a uniform resultCode for closing child activities. Eg. you make 911 (should be int) as your resultCode. If you want your Activity to finish and go back directly to parent Activity, you set the resultCode to 911:
setResult(911); finish();
In every child activity, you override the onActivityResult and check if the resultCode is 911. If yes, then call the setResult(911); finish(); until you get back to your parent activity. Hope this helps!
For example, if you want to start intentB, you can do following in old activity:
Intent intentB = new Intent();
intentB.setClass(XYZ.this, abc.class);
intentB.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intentB);

How to finish all child activities from parent in android [duplicate]

I'm new to android. Actually one handler is running in Home Activity A for every 30 sec to check the net connection.
If I'm went to activity C by A->B->C, If there in no net connection at that time, then i want to close Activity B and C, then want to show message box in Activity A.
But My problem is My handler is running for every 30 sec in Home Activity A. But If i was in Activity C or some other Activity how to find which activity is my Application currently focussed now. Then i want to finish those child activities and want to show Home Activity A I have some 9 child activities in Activity B.
I heard about using "FLAG_ACTIVITY_CLEAR_TOP" . I used the code as follows in the handler in Home activity A itself. But got error.
Intent intent = new Intent( ctx, Homepage.class );
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP |
Intent.FLAG_ACTIVITY_CLEAR_TOP);
ctx.startActivity( intent );
Here Homepage.class is my Home Activity A and i set that activity in manifest file as
android:launchMode="singleTop"
Please help!
You can start Activity A and close all other activities.
You have to create new intent and add flag FLAG_ACTIVITY_CLEAR_TOP
Intent activityA = new Intent(context, ActivityA.class);
activityA.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
context.StartActivity(activityA);
this will close all activities that are in the stack and are at the top of activity A
When calling Acitivity C, call finish in activity B , when calling Activity A from C , call finish() in activity C !
You can use, According to me two ways,
If you start an activity using startActivityForResult, then you can call finish() in this new Activity when you're done with it and it will return control to the activity that started it.
OR otherwise, May be I am wrong,
Call finish inside onStop 'override method'.
make a uniform resultCode for closing child activities. Eg. you make 911 (should be int) as your resultCode. If you want your Activity to finish and go back directly to parent Activity, you set the resultCode to 911:
setResult(911); finish();
In every child activity, you override the onActivityResult and check if the resultCode is 911. If yes, then call the setResult(911); finish(); until you get back to your parent activity. Hope this helps!
For example, if you want to start intentB, you can do following in old activity:
Intent intentB = new Intent();
intentB.setClass(XYZ.this, abc.class);
intentB.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intentB);

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