I'm building a media player. I have a playlist which is an activity with a listview with custom adapter. An item in this listview contains 2 fields : . I want to make the image (playing) visible only for the song which is currently playing(in a service). Also, this should change dynamically whenever the song changes due to any reason even while the playlist activity is open.
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Yes, sufiyan is right about the approach. One thing to add is that when the song changes, you can call notifyDataSetChanged on your adapter to force it to redraw the views to show the selection change.
The biggest expense for drawing a ListView is constructing new item views, but if your adapter's getView uses the 'convertView' parameter then you save that expense. For notifying the activity, I would recommend sending a broadcast from your service. In your activity, register a receiver in onResume, and unregister it in onPause. Then in onResume make sure you refresh (in case the song changed while your activity was paused.
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Hi im currently building my First android app and i have a problem that i cant solve this past 3 days. so i have MainActivity and on it there is a Fragment with Recyclerview and ArrayList< Item > listOfItem, on this Fragment there is a Floating button that when i click it will take me to SecondActivity there is a edit text on this SecondaryActivity that i have to fill then i will pass the data back to listOfItem.My problem is what method can i call on SecondActivity to create/add an listOfItem when i go back to MainActivity Fragment? I dont want to make Adapter and listOfItem to be static. Is there a way? thanks
Simple, You can achieve this by using Shared Preference.
What you need to do is just save that Edit Text data to Model(POJO), save that Model to Preference and in your Main Activity - Fragment on Resume method show updated data from that Preference.
Yeah here you need to take care of
The fragments onResume() or onPause() will be called only when the Activities onResume() or onPause() is called. They are tightly coupled to the Activity.
For more convient and efficient handling of data from any activity or fragement to any activity or fragment, you can use Event Bus.. Here is link where you will get the details information: https://github.com/greenrobot/EventBus
The best solution would be to start the second Activity for result.
startActivityForResult(ActivityBIntent)
Then checking the result overriding
onActivityResult() on the first activity and updating your list/adapter from it
I have a ViewPager with 2 tabs. Each tab just holds a Fragment with a RecyclerView. The RecyclerView in the first tab holds a list of all Articles while the RecyclerView in the second tab only holds the list of user's favorite Articles. Each Article in the first tab has a button in the RecyclerView row that allows the user to favorite it. I want new favorites to be displayed automatically (without forcing the user to manually press the refresh button) when the user navigates to the second tab. How can I go about doing this? Essentially I need to add / remove items from the RecyclerView which contains the favorites, but from the first fragment.
Things I have tried
Call adapter.notifyDataSetChanged() in the onRefresh() method of the favorites fragment. This works, but the performance hit is big because notifyDataSetChanged() is not a cheap operation. I would like to avoid this if possible.
Tried following this guide, and implemented some interfaces. The problem is, when I try to reference the adapter in my fragment from the containing activity, the adapter is always null. I can post code if needed to show what I was doing if this is supposed to be possible.
Now I am considering using SQLite DB to store changes (favorite removals/additions) in the onClickListeners, and then checking that table in the onResume() method and processing the changes individually, one by one with notifyItemChanged()
Is there a better way to do this?
For SQlite use CursorLoader to load data from SQlite. You can register to be notified when a data changed in a table. Then your loader will automatically load data again. Check this answer. Also check this Thread.
For getting data from internet you can use
Communicate with 2 fragments via parent Activity. Check this and this answer. This tutorial is good for better understanding.
LocalBroadcastManager to notify from one fragment to another fragment.
I'm creating a ListView in Activity A which contains some kind of Post views, each of them have its own like button.
Every post can be viewed in Activity B as a single post (Which I re-read from server because there's more info to present).
I'm trying to figure a way that if a user click the like button on Activity B (Which updates the server & UI of its own Activity (B)),
would update the UI of the same post
(which I have its ID and position in the list ofcourse)
on Activity A. .
Any thoughts?
You have to update your adapter data for ListView in another activity and once you back to Activity A in onResume() you can call notifyDatasetChanged() to your adapter and refresh your ListView with newly updated data.
In the application I am building I have 2 listviews with, among other elements, 2 buttons on every row, one for eliminating that row and the other to pass to another activity using an Intent.
I am detecting clicks on both buttons by setting click listeners on both buttons on the getView method of the Adapter class.
The first button was something I couldn't figure out, because I needed to identify in which listview the button was clicked and the position of the clicked row which I couldn't realize how to do.
The second one I thought would be easier since all I needed to do was Intents.
However I needed to call a method from the activity class (had to instance it) since I couldn't make Intents in a non-activity class.
This last one threw a NullPointerException.
Will post all code & logcat in a while, be right back, any possible help will be appreciated.
I will need to see your code, but basically what worked for me for being able to call intents within the code of the adapter was to use the host activity.
Something like this:
item_new = (TextView) convertView.findViewById(R.id.my_view);
Activity host = (Activity) item_new.getContext();
Intent intent = new Intent(host, MyActivity.class);
host.startActivity(intent);
If you post the code maybe I can give more details
I'm not figure out the entire problem, but if you want to start an Activity from an Adapter you could simply pass the current activity to the adapter constructor (or cast the getContext() to Activity, if you used that as context of your adapter)
In a line of code:
Activity.class.cast(getContext()).startActivity(intent);
I am working on my hobby project to learn more about android programming and stuffs. So i recently ran into a simple problem but couldn't find a solution for it.
My project for now have 2 activity [MainActivity], [CommentActivity].
In MainActivity, I have a listadapter (cusAdapter) will fetch all the content from a database and display it on a listview. Everything works fine there. It will fetch all the comments and total comments for a certain post based on the post id. In the same MainActivity, i have a comment button and a onclick listener which when clicked will bring user to the next activity [CommentActivity] and load all the comments and data needed using another custom adapter. I also have a total comment TextView that will show the total comment fetched by the json and display it in my listview.
When a user posted a comment on CommentActivity, it will save into the database via AsyncTask.
Now the problem is, when i press back button and navigate back from CommentActivity to MainActivity, i use intent with flag (intent.flag_activity_reorder_to_front). So it will never reload the MainActivity again when back button is pressed. Also it will never update the total comment in the MainActivity. What i want to do is when back button is pressed on CommentActivity, i want it to refresh/reload the ListAdapter in MainActivity to fetch the latest data from database.
Also i don't want to reload the whole MainActivity, i just wanna update the view without reloading the whole activity.
I believe there must be some easy way to do this. I can post codes if you guys need it to assists me.
Thank you.
Yes, there is an easy way.
Start your sencond activity using:
startActivityForResult(intent, RESULT_CODE)
use setResult(RESULT_OK) in your second activity after doing the commit of the changes to the database
override onActivityResult() in your first activity to check when the second activity returns properly
update the first adapter as needed.
Hope it helps.
In your MainActivity you could check in onResume to see if the data has changed, as this will be called when you go back to it from the CommentActivity.
If the data has changed, calling notifyDataSetChanged() on the adapter will reload the view with the new data