Dynamically I am creating the linear layout and adding the views to linear layout every 5 sec I need to update data to linear layout from database .
But When I checked the log output it is adding to linear layout but gui is not getting updated for every 5 sec. I am using scheduled fixed timer task .
What should i do ?
I agree w/ the other answer from Dimitar that you probably don't want to do this with a linear layout.
However if you must, are you calling invalidate() on the LinearLayout after adding a new view to it?
If you want to visualize data in your application, you should adapt this data to the UI component that will display it. LinearLayout doesn't sound like a good choice for what you are trying to do.
Most often, in Android this is done by using a subclass of BaseAdapter and displaying the data in a subclass of AdapterView. Changes in the adapted data should be handled by the adapter, and the UI component should be updated accordingly.
If you are using SQLite database, take a look at the classes Cursor and CursorAdapter.
Related
I was wondering if I want to create a simple list of buttons, a recycler view will be needed or if I can make do with a listview. Thank you
The simplest method would be to create the buttons and add them the view. I strongly recommend you to not do it the following example is for demonstratiom purpose:
onCreate...
LinearLayout root = findViewBy...
for (item: dataList) {
Button btn = newn Button(this);
btn.setText(item.text);
root.addView(btn);
}
In this example Im using a linear with vertical orientation, that should be inside a scrollview.
That is bad because every view is in memory at the same time. If you have just 2 or 3 buttons then there is no problem but if the number raise to hundreds then there will be memory usage problems.
This is why ListView got deprecated, because every row was rendered. Large data set made the UI slow. Instead RecyclerView literally recyle the views as the name implies. In memory there is only the view on the screen and a bit extra, so when a view leaves the window is available to be reused by the incoming row.
By the comments I can see you are also confused with views and viewgroups. A TextView is a View it can not have another View inside. If you only need to have a click, then TextViews can use a setOnClickListener, other is the case if you need the appearance of a button. Anyway, when you create an adapter you can add any layout you want.
A list of buttons can be achieved in both the ways. But ListView is outdated. So better use RecyclerView
I have views with hundreds layouts (Linears with TextViews), basically it's like list with data.
My presenter after querying the database (sqlbrite, rxjava, its asynchronous) calling method on view which simply create linear with textviews and adds it to some other Linear (its parent for every added view)
With 100+ rows of data on my older phone there is a freeze. How can I reduce it? I can't add views on other thread than UI of course.
First thing you need to use a recycler view for list of views. and ofcoarse you can use 100 different types of views with ViewTypes of recycler view
Second if you insist not to use recycler view then you may better use AsyncTask for adding views at least. Because in some methods of AsyncTask you can access the UI thread and can add elements.
Third possibility is with event bus. you will add a method to the fragment/activity and register it with event bus. make it run in background from the tag(java tags). and call it from background thread for adding items(views)
Hope some of it solve your problem :) if not get back to me with more explanation of the question.
P.S EventBus is a library work almost the same as BroadcastReceivers but it has more features and its more efficient as well.
I can't use listview because this layout will already requires scrolling. So this leaves me at a problem: how to create my tables.
What I know:
The size of the JSON array
I was going to try to make every cell in XML and do a for loop in the code, but my predicament is that I can't findViewById very well, because the R.id.myId names are difficult to account for, and are integers instead of strings. (probably a problem not as large as I am making it).
So here, I know the server call will return a json array with up to 5 objects in it. How can I populate my view?
I am using a LinearLayout for each row, much like I would be preparing a custom list view in preparation.
Insight appreciated.
Is there a specific reason you need it to be a ListView? If not you could try a LinearLayout with a vertical orientation as the container for your list. Just put the container in your xml and you can programatically add the rows that you generate using addView().
i got the following "problem".
I want to have an activity thats shows me the standings of some teams at a specific gameday.
therefor i would add a spinner and a TableLayout. At the first Start the activity should show the standings of the actual gameday but then you can choose any other gaymeday and the standing should get updated.
Whats the best way to create this activity?
assemble the whole TableLayout with all TableRows and TextViews, give them ids and update those views via id during runtime. Problem: huge unflexible hardcoded layout.xml
assemble the layout during runtime, add ids, update via ids
assemble the layout during runtime. on update remove old views and create new ones
assemble the layout during runtime. on update restart the activity
just whant to know which one is the best. or is there any other way to achieve that
thx Cheetah
If I were you, I'd actually use a GridView with an Adapter. This will abstract away all the handling of layout changes. You just have to worry about mapping your data to appropriate views. This example maps ImageViews to a GridView, but there's no reason you couldn't map to TextViews containing your data in a GridView. Also, because you're using an adapter, you can take advantage of all the Loader classes and they're asynchronous loading capabilities.
In addition, using the approach will allow you program to easily adapt as your dataset changes. You may want to add more data to the table in the future and this approach will allow you to easily do that without having to constantly change your xml layouts.
Does the number of views change? If no. Best way is to use the already existent views and update their values. Try to avoid recreating/reinflating views since that's an expensive task.
I want to create a UI as shown in the below link:
http://i53.tinypic.com/sxksx5.jpg
According to me there can be the following approaches to do it.
There are two tables in this image. The above table should be made in the following way:
One row with two textview in one xml file. Now Inflate this UI using LayoutInflater. Draw It using a loop and set the text according to requirement.
The below table should be made in the following way:
How to make a dynamic table layout using XML
see the above link where It is advised that the 2nd table should be made using the listview.
Now I am confused that this can be made using gridvew, tablelayout, listview. Which one I should prefer and why? In my previous projects I have made this kind of UI almost in the coding. But I believe that a little change in the UI will require lot of change in the code. So I want to make the current UI using the xml. But dont know what approach would be best.
I'd suggest using a ListView. Subclass it and overload the getItem() method to render each column of the table row. You can then easily bind the listview to your data sources. you'll need to create an XML layout resource to describe a row of the table.
To show one table above another, put the listviews inside a RelativeLayout and specify attributes to position them relative to each other.
http://developer.android.com/reference/android/widget/ListView.html
http://developer.android.com/resources/tutorials/views/hello-relativelayout.html