Question

I am facing a problem while updating a ListView via an ArrayAdapter in a Android Fragment.

I have a method handling a .csv that is retrieved from a server. It parses the .csv and does the following:

for(int i =0; i< lines.length; i++){
    String[] words = lines[i].split(",");
        for(int j = 0;j<words.length; j++)
            if ( j%6 == 1 || j%6 == 2)
                getArrayAdapter().add(words[j]);

Using breakpoints, I can see that “words[j]” is a valid String. The method getArrayAdapter is the following:

private ArrayAdapter<String> getArrayAdapter(){
   if (aa == null){
        ListView lv = (ListView)   getCurrentActivity().findViewById(R.id.list);
        aa = new ArrayAdapter<String>(
                getCurrentActivity(),
                android.R.layout.simple_list_item_1);
        aa.setNotifyOnChange(true);
        lv.setAdapter(aa);
    }
    return aa;
}

If the “getArrayAdapter().add(words[j]);” is called, method “notifyDataSetChanged()” in ArrayAdapter is called, as it should:

@Override
public void notifyDataSetChanged() {
    super.notifyDataSetChanged();
    mNotifyOnChange = true;
}

Via its parent it reaches DataBaseObservable that does this:

public void notifyChanged() {
    synchronized(mObservers) {
        // since onChanged() is implemented by the app, it could do anything, including
        // removing itself from {@link mObservers} - and that could cause problems if
        // an iterator is used on the ArrayList {@link mObservers}.
        // to avoid such problems, just march thru the list in the reverse order.
        for (int i = mObservers.size() - 1; i >= 0; i--) {
            mObservers.get(i).onChanged();
        }
    }
}

The array of observers had an “AdapterDataSetObserver” that contains all kind of references to my adapter and ListView. I looked what happens in the onChanged() of AdapterDataSetObserver, but I do not really know what to look at.

My table_fragment.xml looks like:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent" 
  android:orientation="vertical" 
  android:id="@+id/top">
    <ListView android:layout_width="match_parent"
              android:layout_height="0dip"
              android:layout_weight="2"
              android:numColumns="2"
              android:columnWidth="30dp"
              android:id="@+id/list">
    </ListView>
</LinearLayout>

The xml of the activity containing the Fragment looks like:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <fragment android:name="com.example.TableFragment"
              android:id="@+id/table_fragment"
              android:layout_weight="0"
              android:layout_width="match_parent"
              android:layout_height="0dip" />
</LinearLayout>

When looking in the log, nothing strange is there. All seems to go fine, but the screen does not show any of the strings.

What am I missing here? Probably missing something trivial, since I am a newbie to Android.

Answer 1

It turns out that layout_height of the ListView can be 0 (it auto expands). However, in the xml of the activity that contains the fragment, the layout_height could could not be set to 0 (it does not auto expand). I had put that on 0dip as well (after suggestion of Eclipse). Changing to “match_parent” did the job (despite the Eclipse warnings).