Removing elements on ArrayList throw an IndexOutOfBoundsException on ArrayAdapter

I'm developing an Android 3.1 application. I have my custom ArrayAdapter. I want to show a list of names in a ListView. These names are forms that could be download and save it locally. When user download and save one or more, I call `updateFormsNotDownloaded()`. But when I do that I get an IndexOutOfBoundsException. And I think this problem is because I call `notifyDataSetChanged()`. Look at my code: ``` public class FormAdapter extends ArrayAdapter<Form> { private Context context; private int layoutResourceId; private List<Form> forms; private ArrayList<Integer> checkedItemsPosition; private Button downloadButton; public ArrayList<Integer> getCheckedItemsPosition() { return checkedItemsPosition; } public String[] getSelectedFormsId() { String[] ids = new String[checkedItemsPosition.size()]; int i = 0; for(Integer pos : checkedItemsPosition) { Form f = forms.get(pos.intValue()); ids[i] = f.FormId; i++; } return ids; } /** * Called when selected forms has been downloaded and save it locally correctly. */ public void updateFormsNotDownloaded() { ArrayList<Form> copyForms = new ArrayList<Form>(); for (int i = 0; i < forms.size(); i++) { if (!checkedItemsPosition.contains(new Integer(i))) copyForms.add(forms.get(i)); } forms = copyForms; checkedItemsPosition.clear(); notifyDataSetChanged(); } public FormAdapter(Context context, int textViewResourceId, List<Form> objects, Button downloadButton) { super(context, textViewResourceId, objects); this.context = context; this.layoutResourceId = textViewResourceId; this.forms = objects; this.checkedItemsPosition = new ArrayList<Integer>(); this.downloadButton = downloadButton; } @Override public View getView(final int position, View convertView, ViewGroup parent) { View row = convertView; if (row == null) { LayoutInflater inflater = ((Activity)context).getLayoutInflater(); row = inflater.inflate(layoutResourceId, parent, false); } Form f = forms.get(position); if (f != null) { CheckBox checkBox = (CheckBox)row.findViewById(R.id.itemCheckBox); if (checkBox != null) { checkBox.setText(f.Name); checkBox.setOnCheckedChangeListener(new OnCheckedChangeListener() { public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { //Form f = forms.get(position); if (isChecked) { //checkedItems.add(f.FormId); checkedItemsPosition.add(new Integer(position)); } else { //checkedItems.remove(checkedItems.indexOf(f.FormId)); checkedItemsPosition.remove(checkedItemsPosition.indexOf(new Integer(position))); } downloadButton.setEnabled(checkedItemsPosition.size() > 0); } }); } } return row; } } ``` I had three items on forms, but I remove one of them. Why am I getting that exception? This is exception log: ``` java.lang.IndexOutOfBoundsException: Invalid index 2, size is 2 at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255) at java.util.ArrayList.get(ArrayList.java:308) at es.viacognita.adapters.FormAdapter.getView(FormAdapter.java:89) at android.widget.AbsListView.obtainView(AbsListView.java:1949) at android.widget.ListView.makeAndAddView(ListView.java:1756) at android.widget.ListView.fillDown(ListView.java:656) at android.widget.ListView.fillSpecific(ListView.java:1314) at android.widget.ListView.layoutChildren(ListView.java:1587) at android.widget.AbsListView.onLayout(AbsListView.java:1800) at android.view.View.layout(View.java:9581) at android.view.ViewGroup.layout(ViewGroup.java:3877) at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1403) at android.widget.LinearLayout.onLayout(LinearLayout.java:1314) at android.view.View.layout(View.java:9581) at android.view.ViewGroup.layout(ViewGroup.java:3877) at android.widget.FrameLayout.onLayout(FrameLayout.java:400) at android.view.View.layout(View.java:9581) at android.view.ViewGroup.layout(ViewGroup.java:3877) at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1403) at android.widget.LinearLayout.onLayout(LinearLayout.java:1314) at android.view.View.layout(View.java:9581) at android.view.ViewGroup.layout(ViewGroup.java:3877) at android.widget.FrameLayout.onLayout(FrameLayout.java:400) at android.view.View.layout(View.java:9581) at android.view.ViewGroup.layout(ViewGroup.java:3877) at android.view.ViewRoot.performTraversals(ViewRoot.java:1253) at android.view.ViewRoot.handleMessage(ViewRoot.java:2003) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:132) at android.app.ActivityThread.main(ActivityThread.java:4025) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:491) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) at dalvik.system.NativeStart.main(Native Method) ```