Question

My ListView items need to be centered when they are selected, but the top and bottom items stop at the top or bottom of the list. How do I center the top and bottom items?

Here’s my test layout:

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:id="@+id/parent"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent"
       android:clipChildren="false"
       android:clipToPadding="false"
       android:gravity="top" >

       <ListView
           android:id="@+id/listview"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:layout_centerVertical="true"
          android:clipChildren="false"
          android:clipToPadding="false" >
       </ListView>

    </RelativeLayout>

Answer 1

I couldn’t find a solution to the clipping issue so I went with adding a header and footer to the ListView. I changed my ListView height back to match_parent and then, using the post method on my ListView’s parent view, I was able to calculate the height of my header and footer like so:

// this call should be included in the onCreate method
// the post method is called after parentView is ready to be added
// so the parentView's height and width can be used
parentView.post(addSpace(parentView, myListView)); 

private Runnable addSpace(final RelativeLayout parent, final ListView list) {
    return new Runnable(){
        public void run() {
            // create list adapter here or in the onCreate method
            // R.layout.list_item refers to my custom xml layout file
            adapter = new ArrayAdapter<String>(MainActivity.this, R.layout.list_item, values);
            // calculate size and add header and footer BEFORE applying adapter
            // listItemHeight was calculated previously
            spacerSize = (parent.getHeight()/2) - (listItemHeight/2);
            list.addHeaderView(getSpacer(), null, false);
            list.addFooterView(getSpacer(), null, false);
            list.setAdapter(adapter);
        }
    }
}

// I used a function to create my spacers   
private LinearLayout getSpacer(){
    // I used padding instead of LayoutParams thinking it would be easier to
    // change in the future. It wasn't, but still made resizing my spacer easy
    LinearLayout    spacer = new LinearLayout(MainActivity.this);
                    spacer.setOrientation(LinearLayout.HORIZONTAL);
                    spacer.setPadding(parentView.getWidth(), spacerSize, 0, 0);
    return spacer;
}

Using this method I was able to add the proper spacing to the top and bottom of my ListView so when I scrolled all the way to the top the top item appeared in the center of my view.

PROBLEM: My app allows the user to hide the bottom interface element which should make my parent much taller. I am working out a way to make my header and footer taller dynamically but I may need to simply remove the ListView and recreate it with a larger header and footer.

I hope this helps someone from hours of frustration 🙂