Previous activity get destroyed on view-pager page change - android

My Previous Activity gets Destroyed on view-pager page changed(of running Activity). Thus onBackPressed() my App gets closed. I don't want to recall previous Activity explicitly.
Assume FirstActivity then open SecondActivity which has one viewpager . When we change page in view pager in Second Activity then FirstActivity (which is in Background) gets destroyed. so when we come back and back press on SecondActivity application closed

Check whether you have called finish(); after starting the ViewPager activity.
Intent intent = new Intent(getBaseContext(), SomeActivity.class);
startActivity(intent);
finish(); // This will destroy current activity.

You should not use finish() method for your activity while starting a new Activity explicitly. Instead, you should handle your activity every time in onBackPressed() method. if you manage your activities using lifecycle states i think you will not need for further explicit call to your activity.

Related

Check if a previous activity exists

I have an activity. After checking some stuff, I want to go back to previous activity if a previous exists, and if not I want to start a SpecificActivity. How do i do it?
Edited:
Seems like no one is understanding what I meant, so let me rephrase. Lets say I am in Activity A. I don't know if A is the only activity in the stack. If there are other activities, then I want to finish A and pop the activity right below A in the stack into the foreground. If A is the only activity in the stack, I want to start some activity Z. How do i do it?
You have to pass class name as intent extra from both Splash and DashboardActiviy.
In List Activity you have to get the class name using getIntent().
When the user click back button, you need to check the class name based on that you can take decision.
if(name.equalIgnorecase(DashboardActivit.class.getSimpleName()){
//Add your intent
}else{
//
}
This may give you definite solution to you.Give a try
you can simply override the onBackpress()
#Override
public void onBackPressed() {
super.onBackPressed();
startActivity(new Intent(this, Destination_Activity.class));
finish();
}
call the next activity like.
Intent intent = new Intent(this,Your_Next_Activity.class);
startActivity(intent);
then it will call your another activity and your current activity will be on background if you will use finish() after calling next activity it will finish your current activity so don't use finish() after calling your next activity in this scenario.
After that when you press back button it will automatically finish current activity.

How to go back to an already launched activity in android

I want to go back to an already launched activity without recreating again.
#Override
public void onBackPressed() {
Intent i = new Intent(SecondActivity.this, FirstActivity.class);
this.startActivity(i);
}
Instead of doing is there any other way to go back to another activity which is already created, which I get back with " Back button "
Add android:launchMode="singleTop" in the FirstActivity declaration in your AndroidManifest.xml like so
<activity
android:name=".FirstActivity"
android:launchMode="singleTop"/>
You could also try the following if SecondActivity was started from FirstActivity
#Override
public void onBackPressed() {
this.finish();
}
Whenever you start a new activity with an intent you can specify an intent flag like this:
// this flag will cause the launched activity to be brought to the front
// of its task's history stack if it is already running.
intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
or
// If set and this intent is being used to launch a new activity from an
// existing one, the current activity will not be counted as the top activity
// for deciding whether the new intent should be delivered to the top instead
// of starting a new one.
intent.addFlags(Intent.FLAG_ACTIVITY_PREVIOUS_IS_TOP);
When starting SecondActivity do not finish the first activity so when you go back , you will be taken to the first activity.
Intent i = new Intent(FirstActivity.this,SecondActivity.class);
startActivity(i);
On your second Activity, close the Activity calling finish() instead of creating a Intent for the other screen.
By calling finish() the Application will go back in the Activity stack and show the previous Activity (if its not finished()).
Don't call finish() on 1st Activity, when you start 2nd Activity. When back is pressed on 2nd Activity, it finishes itself and goes back to 1st Activity by default. onCreate() is not called for 1st Activity in this case. No need to override onBackPressed() in 2nd Activity.
However, Android can destroy 1st Activity when you are using 2nd Activity, to reclaim resources, or, if you have checked Don't keep activities in Developer options. In such case you can use onSaveInstanceState() to save data and onRestoreInstanceState() to use it again in 1st Activity. You can also get the saved data in onCreate(). Here is how it works. Also, onSaveInstanceState() is called only if android decides to kill the Activity and not when user kills the Activity(e.g. using back button).

How do you bring back a destroyed activity?

I have an application that starts activity A. The user can then start service S from activity A. When a certain event happens, service S starts activity B. Activity B only has one button, and when pushed, should return to activity A. Everything works fine, except for when activity A was closed out using the back key. When the back key is pressed, instead of onPause, onDestroy is called. So when activity B is dismissed, I get sent back to the homepage instead of Activity A. So my question is, how can I make sure that Activity B reopens activity A if activity A is onPause, and also reopens the activity A when it's onDestroy has been called. I'm thinking to use intent filters, but I can't figure out to get the right combination. I do not want multiple instances of Activity A. Thanks for the help.
on activity A:
public void onBackPressed() {
moveTaskToBack(true);
}
or on Activity B, force it to start activity A,
public void onBackPressed() {
Intent i = new Intent(B.this, A.class);
startactivity(i);
}
but since you implement the first one,
you dont need this last code.
I Hope it helps
Since you don't need to save A state,
you can override onBackPressed() method in B to start A again.
And if you don't want multiple instances of A, use FLAG_ACTIVITY_CLEAR_TOP when you start B.
Hope this helps

why onCreate() is called every time when its started activity is finished?

In my app, there is a activity A, which it's a main activity, also there are several fragments inside A. When you click the images in one of fragments, it will start a new Activity B. When you click back button, i will call finish() to finish the activity and return to Activity A. But when returning to the Activity A, onCreate() of A is called again. Why onCreate() is called each time? As i know, it should be just called once, and then onStart() should be called.
From segment to the Activity B is as below:
Intent i = new Intent(_scontext, ProductListing.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
_scontext.startActivity(i);
getActivity().overridePendingTransition(R.anim.push_out_to_left,R.anim.push_out_to_right);
When click back button in the Activity B, the code snippet is as following:
Intent _gobck = new Intent(_ctx,ProductDisplay.class);
startActivity(_gobck);
finish();
overridePendingTransition(R.anim.push_out_to_left,
R.anim.push_out_to_right);
What's wrong with the code? Am i missing anything?
You are starting the activity again. Remove the following code and it will work.
Intent _gobck = new Intent(_ctx,ProductDisplay.class);
startActivity(_gobck);
Since you already got your answer by #Rajitha Siriwardena but i just want to clear some of the points here,
As i know, it should be just called once, and then onStart() should
be called.
Above sentence is not a true first of all .
There is possibility to for your ActivityA to go in OnCreate even if you finish your ActivityB. If your ActivityB stay in foreground for a long time ,of-course your ActivityA will be in background in that case , so ultimately your Activity in onStop (remember not in onPause) and android Activity life cycle doc says, after onStop if your app want reach your Activity then it will goes in onCreate
So finish() ActivityB would work but there is no guarantee to your ActivityA called onCreate when you do so .
if you remove finish() from your backPress Activity will not be created and you don't need to write Intent it will manage it's back stack it self.

Android : Finish Activity from other Activity

I am having application in which i am using menu , on tap on menu item i am redirecting to specified activity.
I want to make sure that when i am redirected to another menu item my current all activity should be finished to reduce the stackflow of the activity and better performance.
So when i tap on back from my tapped activity from the selected menu activity i should be redirected to another activity and finish current activity.
So i am wondering is there any way by which i can finish another activity from my current activity. Or should i override the OnKeyDown Method..
Any help on this
Thanks in advance
You can do:
Intent intent = new Intent(....) ; // intent to launch the new activity
// fire intent
finish(); // finish current activity
Intent i=new Intent (currentclass.this , nextclass.class);
startActivity(i);
finish();
Use finish() as shown above ,and here we are redirectin to nextclass.class so all activity of currentclass should be finished to reduce the stack over flow ..
and mind it finish() calls onDestroy() .and onDestroy() is executed...and destroy current activity(in my case currentclass)..
also mind it. onDestroy() isn't a destructor (as in c++) .It doesn't actually destroy the object of current activity... That's it....

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