In my app I have situations where I need to get a user back to some activity that preceded(not necessarilly directly) the current one. All of those previous acitivities might need Intent parameters in onCreate.
So, my question is there any easy way to get user back to an activity that might not be the direct previous activity he's been on and is it possible to avoid manual workaround of saving/restoring those previous activities' intent parameters ?
Consider an example: there's a global search-bar that can provide users with suggestions on products; once they hit one of suggested items they get moved on a product-view activity where they can reload this activity with another product - walk through. After a couple of such reloads they might decide to go back to the activity where the search was initiated, but it might not the closest to the current one.
UPD: There also should be a possibility to go back in B activities sequence.
Using startActivityForResult() while loading a new activity and using finish() to close the launched activity on back press can solve your problem.
Related
Situation:
Starting from my host activityA/fragment A, I click on a button to start host activityB/fragment B. Fragment B is a fragment which enables filtering options for Fragment A. After selecting the options, the user can press the navigate up button to return to fragment A.
Problem:
I would like the state of the options selected to be retained when navigating to Fragment B more than once. Since this is a filtering option, it would be preferable to not save this in storage beyond the duration of the application (It's just filtering. Not necessary to keep the information stored for a long time. Just in between navigation).
Things I've tried:
OnSavedInstanceState - realized that onNavigateUpTo() / finish() don't trigger onSavedInstanceState
android:launchmode="singleTop" - Because the activity is finished and destroyed from the backstack, no instance of the activity is available to receive the new intent.
setRetainInstance - Activity is destroyed so attached fragment also destroyed.
A possible solution I've found is to use setResult and return the values to Fragment A. Then put these values as EXTRAs into a new intent when starting Fragment B again. This solution seems clunky. Is there a cleaner solution that just allows Fragment B to "remember" its state instead of passing values back and forth?
As you have stated the fragment is destroyed when user goes back so there is no way to get the "state" back. Also it does not make sense to store state as logically the fragment/activity is not needed from platform point of view.
So the way to 'remember' the state of fragment is to store the filter data in some other variable(s) and give it back to it when it is re-launched. What you are trying to do it perfectly fine i.e. return the filter data as result and send it back to fragment at re-launch.
To make it simpler you may write a class containing all the filter options and make it Parcelable. You may choose to make it a global so that you may not need to send it across activities, I would not prefer to do that though.
One UX issue is when user presses up/back it is generally expected that user has cancelled the operation. I as a user expect when I press back it cancels the operation and when I press "apply" it applies the filters. You may need to rethink about the user experience about applying filter on back press.
As Android newbie I started to wonder about the Activity lifecycle. I'm having an Activity that loads a list of Persons and displays them. Upon the click of a Person I want to open another Activity showing the details of that Person. I'm currently doing this by creating an Intent on the "PersonDetailActivity" which I then start. So far so good. On the PersonDetail page I would like to have a menu action to go back to the Person list. I again applied the same technique, meaning an Intent that brings me back to the PersonListActivity.
Now I started to wonder what returning to the PersonListActivity means. Will a new instance get created and will I have to reload the persons that it displays in the list? Can you come back to the same instance, avoiding having to reload the list again? Do you then have to pass a pointer to yourself via the intent to the other Activity?
So when will and Activity be re-instantiated and when will it not. Any hints or suggestions are more than welcome. Maybe there are some patterns to be applied for these back and forth menu actions that I'm not yet aware of.
Thanks,
Vincent
Yes,,. Call finish() in second Activity instead of starting new Activity..
There is basically something called Activity stack which stores all Activities in the order they were started.. so if start new Actvity , that sits on top of the stack and preveous one gets below it.. when you call finish the Activity is poped out..
if you don't want to call finish() correct waht ever you were doing then add flag ACTIVITY_CLEAR_TOP in manifest for the 1st Activity..
Basically if you just call the finish() method on your PersonDetailActivity
PersonDetailActivity.this.finish();
it will activate the onResume() method from the Activity that is on the top of the finished one, which here would be your PersonsActivity. You can specify in your onResume() method what you want to perform when turning back there.
Pseudocode :
The initial Activity starts. (ActivityStartScreen)
A button is pressed that starts a new Activity (ActivityOtherScreen) by using an Intent.
The new Activity has a button that loads the initial Activity.
My question is, is the original activity gone once it 'loses focus' (when the 1st button is pressed), or is it stored somewhere, and is there a way to retrieve it?
Currently, Im re-creating the original activity with an intent. I bet this isnt the proper way.
The previous Activities are stored in the Activity stack, to return to previous activity, just call finish() on current activity. Note that this way you lose the 2nd activity.
You simply must call the finish() method from your second activity to go back with the states all being the same.
Here is a helpful warriorpoint blog post tutorial that will walk you through it.
In an app I have very reused Activity, that shows a list of stuff happening on a specific day. The day is specified using Intent Extras.
My problem is, that if the user starts at day=1, then chooses day=2 and then day=1, from the menu, then I would like the back button to go to day=2 and then home. That is, I want to do REORDER_TO_FRONT, but not just based on the name of the activity, but also its extras.
There doesn't seam to be any intent flags suitable for this purpose. I've considered implementing my own 'sub activity stack' using onNewIntent, but it probably wouldn't work very well.
Have you tackled similar problems in your apps? Is there perhaps a way to programmatically access the activity stack, and choose which one is suitable to return to?
Manage your own Activity stack! If I'm not mistaken, you use the same Activity to display each day. Make it single top (FLAG_ACTIVITY_SINGLE_TOP). In the launching intent, pass on the current stack, in your example "121".
Respond to the back button event by launching your Activity with a smaller stack: "12" - or if stack is already "", then just let the Activity handle Back event. Then as you mentioned, use the onNewIntent function to update your Activity.
I'm making an app which has a flow roughly as below:
User starts on the main screen with an empty list, hits menu, and goes to "add item." (Activity A)
User is given a new activity which allows them to specify search criteria, then hits "go" to do a search. (Activity B)
User gets a list of results, and can click on one of them to view more details. (Activity C)
User sees details of item, and can use a menu item to save it to their list in Activity A. (Activity D)
Right now, I am having each Activity call each other Activity for results, and then it is passing the result all the way back up the stack as it returns to Activity A.
Is there a way to jump this, since all I want is for a result in Activity D to get to Activity A directly?
Note that a user should still be able to navigate backwards (using the back button) through each activity, but if they explicitly save the item in Activity D, I want it to jump straight to Activity A.
I recommend just invoking the activities (not using the *ForResult) calls, then having activity D invoke Activity A with an INTENT_ADD_ITEM with data, then have Activity A add the item.
Hope this helps...
Just so that people can benefit from what I learned later...
The key to solving this problem is using flags with Intent, in this case using FLAG_ACTIVITY_CLEAR_TOP. Other flags are useful as well in controlling the flow of your UI.
It is a bad idea to try to solve this problem by chaining startActivityForResult() through activities. It means that it's difficult to change the flow of your application.