I have a problem with an expandable list that uses the application.
My list, throws me an error when I start to show / hide different groups. Then he throws me an error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
I dont know why it shows me this error, beacuse if my convertView does not have a holder, then it create new :(
First it uses List_Kategoria file that is used to store category.
Secondly, I have a few lists that represent several layouts. They are entered in the category.
Here are a few methods of Expandable List View.
@Override
public Object getChild(int groupPosition, int childPosition) {
ArrayList<Object> lista = catList.get(groupPosition).getItemList();
Object obj = lista.get(childPosition);
return obj;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
ArrayList<Object> lista = catList.get(groupPosition).getItemList();
Object obj = lista.get(childPosition);
return obj.hashCode();
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
ViewHolder holder = null;
ArrayList<Object> lista = catList.get(groupPosition).getItemList();
Object obj = lista.get(childPosition);
if(convertView != null) {
holder = (ViewHolder) convertView.getTag();
}
if (convertView == null || convertView.getTag()==null) {
holder = new ViewHolder();
if(obj instanceof List_item_alarm_4 ){
convertView = inflater.inflate(R.layout.list_item_exp_alarm,null);
}
if(obj instanceof List_item_wyswietl_0){
convertView = inflater.inflate(R.layout.list_item_exp_temp,null);
}
if(obj instanceof List_item_tempzad_1){
convertView = inflater.inflate(R.layout.list_item_exp_temp_zad,null);
}
if(obj instanceof List_item_went_wyswietl){
convertView = inflater.inflate(R.layout.list_item_exp_went_wyswietl,null);
}
if(obj instanceof List_item_went_zad){
convertView = inflater.inflate(R.layout.list_item_exp_went_zad,null);
}
convertView.setTag(holder);
}
if(obj instanceof List_item_alarm_4 ) {
holder.item_alarm = (TextView) convertView.findViewById(R.id.item_alarm);
holder.item_alarm.setText("asd");
}
if(obj instanceof List_item_wyswietl_0){
holder.item_temp_0_nazwa = (TextView) convertView.findViewById(R.id.item_temp_0_nazwa);
holder.item_temp_0_wartosc = (TextView) convertView.findViewById(R.id.item_temp_0_wartosc);
holder.item_temp_0_nazwa.setText("temp");
holder.item_temp_0_wartosc.setText("XX");
}
if(obj instanceof List_item_tempzad_1){
holder.item_tempzad_1_nazwa = (TextView) convertView.findViewById(R.id.item_tempzad_1_nazwa);
holder.item_tempzad_1_nazwa.setText("conv");
}
if(obj instanceof List_item_went_wyswietl){
holder.tv_wentRodzaj = (TextView) convertView.findViewById(R.id.tV_went_rodzaj);
holder.tv_wentPrad = (TextView) convertView.findViewById(R.id.tV_wentPrad);
holder.tv_wentCzest = (TextView) convertView.findViewById(R.id.tV_wentCzest);
holder.tv_wentRodzaj.setText("asd");
holder.tv_wentPrad.setText("asd");
holder.tv_wentCzest.setText("asd");
}
if(obj instanceof List_item_went_zad){
holder.tV_wentRodzajZad = (TextView) convertView.findViewById(R.id.tV_went_rodzaj_zad);
holder.eT_went_niski = (EditText) convertView.findViewById(R.id.eT_went_niski);
holder.eT_went_ekono = (EditText) convertView.findViewById(R.id.eT_went_ekono);
holder.eT_went_komfort = (EditText) convertView.findViewById(R.id.eT_went_komf);
holder.tV_wentRodzajZad.setText("NAWIEW");
holder.eT_went_niski.setText("10");
holder.eT_went_ekono.setText("10");
holder.eT_went_komfort.setText("10");
}
return convertView;
}
@Override
public int getChildrenCount(int groupPosition) {
int size = catList.get(groupPosition).getItemList().size();
return size;
}
Here are method which i use to init Data
private void initData() { catList = new ArrayList();
List_Kategoria cat1 = createCategory("NAME",0, "R.mipmap/ic_launcher");
cat1.setItemList(createItemsCat1());
catList.add(cat1);
List_Kategoria cat2 = createCategory("NAME",1, "R.mipmap/ic_launcher");
cat2.setItemList(createItemsCat2());
catList.add(cat2);
}
private List_Kategoria createCategory(String name, long id, String imgPath) {
return new List_Kategoria(id, name, imgPath);
}
private ArrayList<Object> createItemsCat1(){
ArrayList<Object> result = new ArrayList<Object>();
List_item_wyswietl_0 Dana1= new List_item_wyswietl_0(0, "Dana1", "xx.x");
List_item_wyswietl_0 Dana2 = new List_item_wyswietl_0(1, "Dana2", "xx.x");
List_item_tempzad_1 Dana3 = new List_item_tempzad_1(2, "Dana3", "xx.x");
result.add(Dana1);
result.add(Dana2);
result.add(Dana3);
return result;
}
private ArrayList<Object> createItemsCat2(){
ArrayList<Object> result = new ArrayList<Object>();
List_item_wyswietl_0 Dana1 = new List_item_wyswietl_0(0, "Dana1", "xxx");
result.add(Grzanie);
return result;
}
I checked again this app, and i have the error if i have 3 group or more, if i have 2 group everything is ok :)
If i have 3 groups with the same List_category that everything is ok :(
If i have groups, which one group has few different list element that i have problem with that Why ??? :(
