I have a view pager with two tabs in my app (A and B). The first tab i.e A has a listview. Clicking on any of the items in the list opens a new fragment (let's call it C) with another list. The tab B also has a listview.
The list in tab B and the list contained in the fragment C have the same type of items. That is each item of both list is of the same class. I have used a recycler view with a custom adapter to create the list. Since both lists in tab B and fragment c are of the same object type I have used the same adapter, namely (CarListAdapter.class) for this purpose.
The problem I am facing is that when I open fragment C then go back to tab A and then right swipe so that tab B is visible, clicking on an item in tab B causes null pointer exception, reason being that the list in fragment CarListFragment.class still has the data from fragment C and not tab B.(However the list is rendered properly, it is only the click that is not working properly)
Since two instance of this adapter are present I expected this to work fine. If however I use two different adapters with exact same code like (CarListAdapterC.class and CarListAdapterB.class) the code works fine.
I am stuck, can someone please explain why this is happening?
I have encountered same problem when using view pager and recycler view. I have searched allot and as i know it's an issue in recycler view adapter.
As you may know view pager load one more next page by default every time it shows a page.and here is where adapter shows the problem.The different instances of a same adapter that you create point to same place.because of that it still has other pages items.
I know it's not a good idea but i have created another adapter same as the first one with different name and used it for the next list and it worked.try to separate your list's adapters.let me know if it works.
I finally found the solution, it was really stupid on my part. I had static fields in RecyclerView Adapter. Removing them worked like a charm.
Related
I have one Activity which contains viewpager inside and each viewpager tab contains one fragment . only one of these fragment has one recyclerview (which has inside cardView)and of course one adapter for the recyclerview . by clicking on floating action button which is in Main Activtiy layout another Activity open that contains two edit texts one for device id and one for device name and one button called Add .by clicking the add button it should add the device to the database and update adapter using notifyItemInserted(position) .... the problem here it add the device to the database immediately but the adapter not update the view immediately . it update after i scroll through the app using viewpager tabs or when i start the main activity from the beginning .... there is no error in the code and i have search for answer but i couldn't find anything to solve this issue ..
anyone face like this problem please advice
thanks
Try swapadapter() method for the same.
void swapAdapter (Adapter adapter,
boolean removeAndRecycleExistingViews)
Swaps the current adapter with the provided one. It is similar to setAdapter(Adapter) but assumes existing adapter and the new adapter uses the same RecyclerView.ViewHolder and does not clear the RecycledViewPool.
Have you tried to call your SetUpRecyclerView in onActivityResult() which I asume your are using. That is what I use when adding elements to My RecyclerViews.
When using FragmentPagerAdapter, Your pager keeps two tabs in memory, that's why you have to scroll for the changes to take effect. But for me calling my SetupRecyclerView works just fine.
I have a ListView that represents a list of folders and when I click one item, I want to load another list that shows the content of this folder. How can I link these views together and to be able to go back to the first one with the back button ?
Well, since you didn't provide a code in your question, I will try giving an answer in a descriptive manner.
You can use fragments to do this. Your base Activity's layout must have a fragment container which you will use to display your fragment containing the first ListView data. Once after you click on a cell, you call the constructor of the second ListView, and replace the current content of the fragment container with the newly created fragment.
You may implement a back feature by implementing an ArrayList in your Activity and appending the fragments into that array list as the user navigates through the list. onBack pressed you can call the top most fragment from that Array list and assign it to the fragment container.
This should work well, given there are not too many types of ListViews that you may want to implement.
I have an app where consisting of a viewpager with 3 tabs, with the second tab containing a recyclerview with items.
If I were to hold onto the item, a dialogfragment would popup. There's an option to delete the item from the database. However, I'm having trouble working out how I would refresh the recyclerview. I've tried creating a new fragment (2nd tab fragment), however, the data doesn't update.
The only thing I can get working is by recreating a new activity, however, that loads the first tab of the viewpager.
Thanks in advance.
im trying to implement an android aplication when your activity, cointains 3 or more 'main windows' like in the image -> 'A'. 'B'.'C'. so how is posible make when you slide you touch screen change from A, to B, for example, i was thinkin in a horizontal view, and inside of each item use a relative layout, but im not sure, its my first time with this kind of problem, thanks.
Try using android ViewPager. Each ImageView would be inside a Fragment that would reside inside your Activity. Check out this example
Use Tabbed Activity template when you want to make this type of Activity. ViewPager, Adapter and tab layout will be automatically implemented for you. Just make small changes in your Adapter according to your needs and use one Fragment for one tab and you can create as many tabs as you want in an Activity.
If you want i will post an example of an Adapter as i just implemented an Activity with 3 tabs.
To get your basics strong on ViewPager, tab layout and Fragment sections adapter read out this link.
I'm a newbie Android developer and I'm trying to create an Android application with 2 tabs, using Activities for each tab. This is basically how it should work:
Tab A has 1 button
Tab B has 1 ListView
When the user clicks on the button in Tab A the application must put a value in the ListView in Tab B
My question is: how can I update the ListView in Tab B when I click on the button in Tab A? I know how to put values in a ListView when it's on the same tab where the button is located but my approach doesn't work when the ListView is in a different tab. I tried...
ListView myListInTabB = (ListView)findViewById(R.id.list_on_tabB);
but didn't work :-/
Any suggestion?
Thanks in advance.
Im not sure you actually need seperate activites for this, unless you are doing some specific work between your activities. Most tab solutions you see in Android solutions work simply by hiding the Views that are not related to the current shown tab. You will find the "visibility" property helpful for making this happen. Also, making sure all of your Views are in the same Activity lets you access their objects all the time, regardless of their visibility.
You don't do that. Just ensure the underlying Adapter has the latest data. Calling requery() on the Cursor does the trick, it automatically updates the ListView attached to it.
Edit: use notifyDataSetChanged() to let the list know that the data is stale.