Expandablelistview Adapter Not Working Properly

Question

I firstly use ExpandableListView view in Android. I want groupviews to have different layouts or items in ExpandableView. Childs consist of spinners, textviews, edittexts.

My problem is when expanding groups, correct layouts dont inflate or the code crashes because of null pointer exception mostly cause spinners. Some codes samples are below

ExpandableListAdapter.java

    @Override
public View getChildView(int groupPosition, final int childPosition,
        boolean isLastChild, View convertView, ViewGroup parent) {

    View v = null;
    int itemId = (int) getChildId(groupPosition, childPosition);

    if(convertView==null){
        switch (itemId) {
            case 6: convertView = li.inflate(R.layout.expand_akis,null);
                    v = akiskan(convertView);
                break;
            case 9: convertView = li.inflate(R.layout.expand_kapasite,null);
                break;
            case 11:convertView = li.inflate(R.layout.expand_kapasite2,null);
                break;
            case 12:convertView = li.inflate(R.layout.expand_evapohava,null);
                break;
            case 14:convertView = li.inflate(R.layout.expand_evapohava,null);
                break;
            case 15:
                break;
            case 18:
                break;
            default:
                break;
        }

    }
    switch (itemId) {
    case 6: v = akiskan(convertView);
        break;
    case 9: v = kapasite(convertView, childPosition);
        break;
    case 11:v = kapasite(convertView, childPosition);
        break;
    case 12:v = convertView;
        break;
    case 14:v = convertView;
        break;
    case 15:
        break;
    case 18:
        break;
    default:
        break;
    }

    return v;
}

private View kapasite(View convertView, int childPosition) {

        if(childPosition == 0){

            EditText editKapasite = (EditText)convertView.findViewById(R.id.editNumKap);

            Spinner spinKapa = (Spinner) convertView.findViewById(R.id.spinKapa);
            ArrayAdapter<CharSequence> adapKap = ArrayAdapter.createFromResource(activity, R.array.kapasiteler, 
                    R.layout.spinnertext);
            adapKap.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spinKapa.setAdapter(adapKap);
        }
        else if(childPosition == 1){
            EditText editYuzdePlus = (EditText)convertView.findViewById(R.id.editYuzdePlus);
            EditText editYuzdeMin  = (EditText)convertView.findViewById(R.id.editYuzdeMin);
        }

    return convertView;
}

private View akiskan(View convertView) {

    Spinner spinAkiskan = (Spinner) convertView.findViewById(R.id.spinAkis);
    ArrayAdapter<CharSequence> adapAkis = ArrayAdapter.createFromResource(activity, R.array.akiskanlar, 
            R.layout.spinnertext);
    adapAkis.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinAkiskan.setAdapter(adapAkis);

    return convertView;
}

getChildId() function generates unique id according to groupPosition and childPosition

main.xml

<ExpandableListView
    android:id="@+id/expandableList"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@+id/detailAraButton"
    android:layout_alignParentTop="true" />

expand_akis.xml

  <EditText
        android:layout_alignParentLeft="true"
        android:id="@+id/editNumKap"
        android:layout_width="100dp"
        android:layout_height="wrap_content"
        android:ems="10"
        android:layout_marginLeft="20dp"
        android:inputType="numberSigned" />


     <Spinner
        android:layout_toRightOf="@+id/editNumKap"
        android:layout_marginLeft="20dp"
        android:id="@+id/spinKapa"
        android:layout_width="85sp"
        android:layout_height="wrap_content"
         />

expand_kapasite.xml

 <EditText
        android:layout_alignParentLeft="true"
        android:id="@+id/editNumKap"
        android:layout_width="100dp"
        android:layout_height="wrap_content"
        android:ems="10"
        android:layout_marginLeft="20dp"
        android:inputType="numberSigned" />


     <Spinner
        android:layout_toRightOf="@+id/editNumKap"
        android:layout_marginLeft="20dp"
        android:id="@+id/spinKapa"
        android:layout_width="85sp"
        android:layout_height="wrap_content"
         />

LogCat

    02-23 14:11:21.952: E/AndroidRuntime(16384): FATAL EXCEPTION: main
02-23 14:11:21.952: E/AndroidRuntime(16384): java.lang.NullPointerException
02-23 14:11:21.952: E/AndroidRuntime(16384):    at com.buzcelik.tools.ExpandListAdapter.kapasite(ExpandListAdapter.java:105)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at com.buzcelik.tools.ExpandListAdapter.getChildView(ExpandListAdapter.java:76)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.ExpandableListConnector.getView(ExpandableListConnector.java:450)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.AbsListView.obtainView(AbsListView.java:2025)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.ListView.makeAndAddView(ListView.java:1820)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.ListView.fillDown(ListView.java:672)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.ListView.fillSpecific(ListView.java:1378)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.ListView.layoutChildren(ListView.java:1651)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.AbsListView.onLayout(AbsListView.java:1876)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:925)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1589)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1628)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1486)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.LinearLayout.onLayout(LinearLayout.java:1399)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.widget.FrameLayout.onLayout(FrameLayout.java:431)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.View.layout(View.java:11425)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewGroup.layout(ViewGroup.java:4232)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1509)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2498)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.os.Looper.loop(Looper.java:154)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at android.app.ActivityThread.main(ActivityThread.java:4944)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at java.lang.reflect.Method.invokeNative(Native Method)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at java.lang.reflect.Method.invoke(Method.java:511)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
02-23 14:11:21.952: E/AndroidRuntime(16384):    at dalvik.system.NativeStart.main(Native Method)

getChild() function

   @Override
public long getChildId(int groupPosition, int childPosition) {
    return 2*(childPosition+3+groupPosition)+groupPosition ;
}

Thanks in Advance!

Answer 1

The problem is view recycling. You set the views once when they are null. Your assumption is that these views will always be given to getChildView when that view is called in the future. This is incorrect, once you collapse the group those child views are now eligible to become children of another position. The adapter recycles them.

There's an elaborate way to fix this, and a simple way. The simple way is to inflate the view each time getChildView is called, so that you overWrite the previous view. I think you should try that first, so you can understand that this is the problem.

The more elaborate way is to override getChildType() and getChildTypeCount() and force the former to return a unique identifier for each layout you want (similar to what you are presently doing with getChildId), and make getChildTypeCount return a value equal to the number of unique layouts.