I have a setup as follows
Activity 1 uses a ListView and ListAdapters to display information
from list of objects of type A (by retrieving from the database the first time its called).
Upon clicking an item in the ListView in Activity 1, the control goes
to Activity 2, which again uses a ListView and ListAdapters to display
information from list of objects of type B.
There is a '+' button in Activity 2, which when tapped switches the
control to Activity 3. Here I can create an object of type B and save it to the database.
Now I use the setResult() in Activity 3 and onActivityResult() in Activity 2 to update the list in Activity 2.
So far so good. I can see the item of type B that I just created in Activity 2.
Now if I press the back button and go back to Activity 1, and tap on
the same item of type A then when I go to the Activity 2, the item that I had just created
does not show. However when I close the app, and open it again, and
follow the same path, I can see that item. (As the list was reloaded from the database)
So how do I update the list in Activity 1?
I hope I explained my question properly (apologize if not!). I don't want to put all the code here, since there is no issue with the code, unless my approach is wrong.
Put your code which loads the list from database in Activity.onResume() method. This way it should execute every time your activity is restored from invisible state (take a look at the docs on activity lifecycle for more info).
Also, you might want to implement loading from database using Loader. It monitors the data source for updates, thus keeping data up to date.
Related
Example:
This is a Main Activity and onclick item from adapter class its open second activity having listview but in case there is no data in listview for any of the item of grid activity then skip second activity and goto third activity directly. [1]: https://i.stack.imgur.com/OrbTJ.jpg
[1]: [Second Activity][1] https://i.stack.imgur.com/KEfEF.png
[1]:Third Activity https://i.stack.imgur.com/XSYMB.png
If I correctly understand what you mind in the comment section, this follow would be ok:
In Activity-One:
When the user clicks an item -> fetch data & show loading. When data fetching ends, hide loading and check data size to decide starting activity second or the third one.
It is not possible directly, You need to know before if there is data in list or not or you need to move to secondactivity ofr 1 sec and then can navigate further.It will look like skip.
i am struggling to keep data or items of list view when i leave one activity to another, for my example i created simple app on click will add number increased to a list view so each click create an item like 1 another click add 2 and so on.
the program works fin for main activity but then i would like to see the result on another activity i call it second activity but the problem is when i hit back button on second activity to go back to main activity, i will lose all of items on the list view.
i was looking on google so many information but could not get my head around it, so please advice and please be little more in detail as i am beginner, i think instance state or shared preference will do the job but i do not know any of them
thanks in advance and here is my app code for main activity and second activity and picture for output
sorry i add code as images becausethe site keep saying the code need indentation thank you
main activity[main out put][2]second activity[second activity out put][4]
You need to save the data of the ListView in some form, either in a file or in a database (local or remote).There is no direct way to store list view, but you can store the data from the list view and then set it in to the ListView later when you switch back to the activity.
You need to keep in mind that switching activity results to invoking of onPause() method in android, and if the data is not saved in the current activity then it will be lost when you move on to another activity.
Add all your values into the array, pass it to the adapter, then after clicking on the list view item, make an intent where you want to switch your activity (means from one activity to second activity), while implemented the intent, pass your array also, using intent.put extra. Then you will get your array in your second activity and coming back to your previous activity, again pass an intent (with your array) and get your array in your previous activity and pass it into the adapter.
I was wondering if it is possible to save multiple instances of activities in a list as in when a user selects an item in a listView it opens up its corresponding activity that was activated earlier.
To give you a sense of where I am coming from here is the concept of the app I am making.
In Main Activity there is:
A button that when pressed launches a new activity called Exercise
A fragment WorkoutsFragment that keeps track of a list of prior workouts.
In Exercise Activity (whose parent activity is main activity):
Users can input what exercises they are doing in the activity.
When the user goes back to main activity a new item is added to the list in WorkoutFragment and that item contains a summary of the exercises done in the prior Exercise activity. When this item is pressed I want it to go back to the Exercise activity created earlier with all information retained.
So if a user presses the workout item for June 12 I want to to resume the Exercise Activity that was created on June 12.
Would it make more sense to just start a new exercise activity and populate its contents from a database?
You are thinking right. The right way to do it is to create a new Exercise activity and populate its content from database. Maintaining references to activities is not a good practice.
You can also maintain a cache of recent exercises accessed to avoid the database call.
This seems like a good case for using the Activity onRestoreInstanceState.
See this guide on restoring different states of an Activity:
https://developer.android.com/training/basics/activity-lifecycle/recreating.html
You may pass basic data between your Activities through the Intent extras.
How do I save previous activity and have that update into a listview so that when a user launches the app at a later time he can click on a menu option called history which will bring a listview of the last few activities. Let's say the listview holds 5 activies and after the 5 activies it deletes the oldest activity saved and saves the new activity in it's place.
For example if someone wants to view history of an android activity that he viewed two days ago, he can simply click on a button called history and view his past 5 entries which will be displayed in a listview.
Any ideas?
You can't do it by default Android Activities method.
Just save state in onResume/onCreate (as file in filesystem or SharedPreference) and read it from yours History Activity.
Sorry for bad english)) Ask if don't understand something.
In my application Activity A has a list of items
on choosing a product i go to activity B that give details of that item and a button "Choose this item"
which will go to activity C.
In actvity C this choosen item is displayed and there is a button "choose more items"
on clicking this i have to go back to activity A, and repeat the same steps.
BUt when another item is choosen, activty C should display both items.
SO i thought from actvity C, i start activity A, by calling startActivityForResult() and add the result to existing list of items.
In that case, i have to call finish() of A to retrn value.
Is this right way of implementing
Since "choose more items" can be clicked many times in real life, wont it end up killing and starting many times the same activity
I have set the launch mode as single task for the activities
What would be the best way to handle this situation
thanks a lot for your time and help
Well, I will suggest that you can take a static List or ArrayList and work accordingly.
1.) You can take a public static List and can initialize as per your requirement, something like this.
public static List<CartListClass> cartlist = new ArrayList<CartListClass>();
2.) You can access this from any class using Acitivity_name.cartList and add the required information.
3.) Now, when you will come to Activity C you will have all the required information in the static List, so from there you can get and show the required Details of the product.
And, the static List will maintain the information also, when you select another product or item from Activity A to Activity C, it will be added to the List below the previous item or product.
UPDATE:
Better approach would be using BroadCastReceiver to update the value or using Interface.
I would save identifiers of chosen items in Activity C to preference.
So, in resume of Activity C, I'd check how many I have in the saved preference and load corresponding data to views.