Develop Reference

Android Listview : Center items in layout when fewer items

I have a listview that can have items from 1 to 100, dynamically varying.
However, when I have fewer items, I want the items to appear vertically centered in
the listview layout. By default, Android draws the items form the top. I have attached a picture to illustrate what I need.
Is there any way I can achieve this, either by code or in XML layout ?
Thanks.
Edit: Based on the answers I have received now, I am adding more clarity to my question as the answers are off mark.
The positioning of the Listview in the main layout or positioning of individual item layouts is not an ISSUE here. The listview is positioned properly as shown in the shaded background. The question to which I need answer is:
Assume there are 10 items, the entire shared area of Listview will be used by items,
possibly Items 1 to 5 are shown.
Assume there are 3 items only. The listview is still shown but Items 1,2 and 3 are rendered at the top of the listview (shaded area). However, in this case, I want the items to be drawn at centre of the listview's layout (as shown in the picture).
Anyway this can be done ?

Use this property
mLoginUserNameValueView.setGravity(Gravity.CENTER_HORIZONTAL);
which one you want to center in the List view adapter and which position exactly where you need
e-x you need your 55th position you want center the item means
in getview you will use this line like below.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
convertView = null;
if (convertView == null) {
convertView = mLayoutInflater.inflate(R.layout.navigationlayout,
null);
mHolder.mLayout = (LinearLayout) convertView
.findViewById(R.id.navigationLayout);
mHolder.mNavigationtext = (TextView) convertView
.findViewById(R.id.navigationText);
convertView.setTag(mHolder);
}
if (\\Your desired position checking )
\\ and set the above line here
}
return convertView;
}

Adapter's getView() asks for position 0 twice before each postion. Why?

I read all the other posts on getView() and didn't find any solutions. I have a GridView with a SimpleCursorAdapter. I log(position); in getView() and I see a pattern like this:
0,0,1,0,0,2,0,0,3,0,0,4,0,0,5 etc. This means I'm having to build 3 views as it scrolls for every new view displayed and it's choppy and laggy. Why does it do this? I don't have anything obvious like setting my gridview to wrap-content or anything else weird. There's nothing strange about my code. One thing that might be a factor is that every item view could have a different height depending on the length of the text I'm displaying.
I'm currently debugging on a 4.2.2 Galaxy Nexus.

Index 0 is requested in gridview measure/layout pass.
The question doesn't have the details, but the following could explain the pattern you're seeing:
The GridView is in a layout that requires two measure/layout passes (e.g. LinearLayout with weights, RelativeLayout with layout dependency rules). This explains the two position 0s.
Each getView() causes the parent to re-layout. This explains the position 0 after each position.

make sure that the height of your listview is not wrap_content
and make it fill_parent .
Hope that helps .

As I wrote in the question's comments, I noticed that getView() is invoked on position 0 even though that position is NOT seen at all. I think the reason is the need to measure the items by the grid.
It doesn't bother me that much that this happens a bit, but it bothers me when it's done a lot and when scrolling down the grid, making the grid leggy. Especially when it repaints elements that aren't even seen.
The way I solved it is that when getView(0) is requested and item 0 should not be seen, meaning a measurement is done, I return an actual view which was already painted (reusing the converted view), avoiding repainting position 0.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// Workaround Android requesting position 0 even though it doesn't draw it.
AbsListView listView = (AbsListView) parent;
int firstVisiblePosition = listView.getFirstVisiblePosition();
if (position == 0 && firstVisiblePosition > 10) {
if (convertView == null) {
convertView = actualPaint(position, convertView, parent);
}
return convertView;
}
convertView = actualPaint(position, convertView, parent);
return convertView;
}

Best way to build and handle List view with differing rows

In my app, I show data in a list view. It looks as below.
Each row in list view is different (ie., they have a different view structure). But every row is made up of 1 to many subviews (all subview are same ).
Problem: If try to inflate the rows from xml then I need to have xml with
1. 2 subviews
2. 3 subviews
3. 5 subviews and so on
If I try to build the rows dynamically then I wont be able to take advantage of the holder pattern or the views re-usability of Listview. And I will end up building the subviews if the number of subviews, in the returned view is less than required or deleting in case the subviews are more than required.
In a nutshell, how can I have different views in listview which does not hamper view re-usability or holder pattern ?
Edit:
I have extended ArrayAdapter and overriden getView, getViewTypeCount, getItemViewType
#Override
public int getItemViewType(int position) {
return mListItems.get(position).getViewToBeRenderened().getViewId();
}
#Override
public int getViewTypeCount() {
return AppConstants.VwViewTypes.values().length;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
final VWListItem listItem = mListItems.get(position);
if(listItem == null || listItem.getViewToBeRenderened() == null){
return convertView;
}
VWView renderingView = listItem.getViewToBeRenderened();
if(convertView == null ){
convertView = renderingView.buildView(mContext.appContext);
}
...
}
This approach worked initially when there were only 2-3 differing row views. For each of these row views i had a different xml layout and corresponding class which would build and inflate.
But now the number of such views is growing and I dont want to have a layout and class for each additional new row view. Instead I would like to reuse existing layouts and class and build on them. If there is a better solution then am open to it as well.

when you have to manage different kinds of views you should override getViewTypeCount() and getItemViewType() and you will receive a number of convertViews equals to the int returned by getViewTypeCount(). For instance, If it returns 2 you will get 2 differents convertView.

ListView is supposedly used to relieve the coders of some burden when each row has similar repetitive pattern. Yes, for slight variations getViewType is the correct choice to implement, but I see a better solution to your problem: you should create your own linearlayout if you have a lot of customization requirement. Remember that listview itself is an expensive object to create. Create a custom linearlayout is not that hard.

listview recycling strange empty space

I have a similar problem to the one in this question: ListView and rows recycling problem
Above is solved. but same solution does not work for me.
I have a listview consisting of textviews. Each textview can contain variable number of images. I am getting images with html.imagegetter and I am using recycling in getview method of list adapter.
If there is one or more images in a textview, it will have a height to be able to fit its content. When this textview is recycled and new content does not fill the height defined before, then empty space will appear.
The problem is that I can't restore the textview height in getview because I dont know what height the next list item will have.
this is my getview:
public View getView(int position, View convertView, ViewGroup parent) {
final ViewHolder holder;
View rowView = convertView;
if (rowView == null) {
LayoutInflater inflater = context.getLayoutInflater();
rowView = inflater.inflate(resource, parent, false);
holder = new ViewHolder();
holder.imgAvatar = (ImageView) rowView.findViewById(R.id.imgAvatar);
holder.textDetails = (TextView) rowView.findViewById(R.id.textDetails);
holder.textPostTime = (TextView) rowView.findViewById(R.id.textPostTime);
holder.textPost = (TextView) rowView.findViewById(R.id.textPost);
rowView.setTag(holder);
} else {
holder = (ViewHolder) rowView.getTag();
}
holder.textDetails.setText(details.toString());
holder.textPostTime.setText(x.postTime);
holder.textPost.setText(Html.fromHtml(x.postBody, new URLImageGetter(holder.textPost, context), null, context));
return rowView;
}
this is row layout:
<TextView
android:ellipsize="none"
android:autoLink="web"
android:textColor="#000000"
android:id="#+id/textPost"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
THE PROBLEM: The listview recycling mechanism can't calculate the new height for used views according to its new contents.
Without recycling, it is too slow.

So, essentially your problem is with recycling the views. When your views get inflated from XML they look at the images and decide how tall to be. This works fine because the inflater can cause the height to be "wrap_content" aka however tall the tallest child component is - this is dynamic.
However, when your getview recycles the old views it (for some reason) isn't updating the height of the rows, and neither are you (which you never had to do before because the inflater handles it automatically from "wrap_content"). It would appear from what you described that you just get a row with whatever the height of the view happened to be set at previously (this previous value was set by the inflater automatically).
Your two solutions are:
Don't recycle the views - just inflate a new one every time. You will see a performance hit which will probably only be noticeable at lists with ~50 elements or more. If it is a small list this may be the easiest (code-wise) option, although there it will still operate slightly slower.
Keep recycling the views - if you pick this you will have to set the height of the row (or text view, whatever is determining it) yourself based on the image heights. This is doable but will require more work. I'd suggest
secret option 3 - normalize the image heights - If you would a.) like to continue recycling views but b.) don't want to write the code to set the row heights manually and c.) resizing the images wouldn't kill your app, you could use the setMaxHeight(int) method to make sure all of your images are the same height (or use a method like this to resize the images to a predetermined size)
Note: I am pretty sure (almost certain) that, normally, if height is set to "wrap_content" it would wrap to the new content size (since it normally updates the size when the content is updated). I couldn't say why this is not happening for you - it may be that something inside the "wrap_content" has its size set to a concrete value and thus isn't resizing, so the "wrap_content" isn't changing even though there is empty space.

Try using requestLayout on your image and textviews. It will help the listview recompute the height of recycled views.

Android HorizontalScrolling laggy

I have a HorzontalScrollView with a LinearLayout inside. During Runtime I can add more LinearLayouts to the LinearLayout.
Now I have the problem that the Scrollview only scrolls a little bit and not smooth with one finger slide!
Does anyone have a solution for this problem?

HorizontalScrollView doesn't use an adapter that manages the list's memory, therefore it can't handle heavy (images, custom views, etc) lists.
You can use this Horizontal ListView http://www.dev-smart.com/archives/34 but make sure you don't write the on list item click method inside the getView, it will make the list scroll slow. Other than that, that's a great resource for a smooth horizontal list view.
You can also explore the Android view pager, which is also supported on lower Android versions using the compatibility pack: http://developer.android.com/sdk/compatibility-library.html
Edit - something like that in the adapter that inflates the XML you want (the linearLayout) and then populates every view with the relevant data.
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.chat_friends_list_item, null);
}
ImageView status = (ImageView)convertView.findViewById(R.id.status);
ImageView image = (ImageView)convertView.findViewById(R.id.image);
ImageView imageBorder = (ImageView)convertView.findViewById(R.id.image_border);
TextView title = (TextView)convertView.findViewById(R.id.title);
}

The problem was my parent Viewflow because it has stolen the swipe event! The HorizontalListView is too buggy for me! (Problems with size attributes)
However,thank you for your answer! ;)