Develop Reference

Android Adapter for single item like ArrayAdapter is for a list?

What Adapter should I use for a single item? I use the ArrayAdapter for rows items. Is there a simple adapter I should use when displaying just one item?

If u want to display single item then simply use text view and make it visible or invisible as per the logic of your code.

ListView with horizontally scrollable views

I'm currently developing an app in android.
I have a really basic listview that has 3 elements in his adapter:
1 imageview and 2 textviews.
These 3 items are inside a constraint layout.
All i ask is if i can make this layout (imgview + 2 tview) scrollable horizontally.
I've tried adding the layout to a horizontalscrollview, it works but i can't take the list onclicklistener.

I assume you want to be able to click on a list item? You could try adding a click listener to the scrollView. You probably also need to set clickable = true on the scrollview (not sure which is the default) and also just in case set clickable = false to all 3 child elements so they don't "eat" the click instead of the scrollView.

Use RecyclerView instead, you can add the onClickListener inside the adapter itself, or if you want the clickListener to be more interactive between your adapter and your activity/fragment, you can try using interface inside the adapter.

Remove all added views from ListView

I am adding a view to my ListView with the following code:
((ViewGroup) myListView.getParent()).addView(createMyCustomView());
My question is how to clear all the added views? I've tried removeAllViews() but it's not working.
I need to add the view to my ListView so that I can set its empty view with:
myListView.setEmptyView(createMyCustomView());

Clear the items from the list you are using in your adapter, then call notifyDataSetChanged() on the adapter. Checkout this similar question.
Let me know if this helps, or if you need more information!

Array list adapter with button objects

I am new to android app development.i want to create a list view that has only one button per cell of list view.For the adapter of this list view i need to give 'ArrayList' as parameter so that I can add and update list view whenever I need.

Take a look at this tutorial for custom listView.
You can put the button or anything you want in rowlayout.xml

What kind of layout and java class should i use for a friend list layout?

I am learning android development and i am kinda stuck here. I want to create a friend list screen like shown in this picture.
What kind of activity should i use? Is there any available resources similar to what i want to achieve?
Thanks!

you can use ListActivity , also check out tutorials on lists, for example:
http://www.androidhive.info/2011/10/android-listview-tutorial/
http://www.vogella.com/tutorials/AndroidListView/article.html
you can find mire tutorials on google.
also you can use a regular Activity class with listView in the layout file

Use list view and custom adapter to populate the list view...
Listview should extend to the bottom but limit it just above the Type a name edit text and button.
Custom list view should contain linear layout horizontal in that include checkbox, Textview and Button
For type a name and Add use linear layout horizontal

Use listView with custom adapter , for array use arrayList<,friends,> sure you have to create friends class, in xml file put ListView then below that button and TextView