Everything was working fine but now I am not getting what is happening,I have 10 items to display in the listView,its working fine till the 6th item and after that it repeats again from the 1st item again??
public class GroupDetailsAdapter extends BaseAdapter {
List<GetSetGroupDetails> group_details = new ArrayList<GetSetGroupDetails>();
Context context;
Typeface face;
public GroupDetailsAdapter(List<GetSetGroupDetails> group_details,
Context context) {
super();
this.group_details.clear();
this.group_details = group_details;
this.context = context;
face = Typeface.createFromAsset(context.getAssets(),
"HelveticaNeueLTStd-Th.otf");
}
@Override
public int getCount() {
// TODO Auto-generated method stub
int count = group_details.size();
return count;
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v = convertView;
ViewHolder holder;
if (v == null) {
try {
LayoutInflater vi = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.group_item, null);
holder = new ViewHolder();
holder.tv_group_name = (TextView) v
.findViewById(R.id.tv_group_name);
String group_name = group_details.get(position).getGroup_name();
holder.tv_group_name.setText(group_name);
holder.tv_group_name.setTypeface(face);
holder.tv_group_reg_id = (TextView) v
.findViewById(R.id.tv_group_reg_id);
String groupRegId = group_details.get(position)
.getGroup_reg_id();
holder.tv_group_reg_id.setText(groupRegId);
holder.tv_group_reg_id.setTypeface(face);
holder.tv_subscriber_count = (TextView) v
.findViewById(R.id.tv_subscriber_count);
holder.tv_subscriber_count.setText(group_details.get(position)
.getSubscriber_count());
v.setTag(holder);
} catch (Exception e) {
e.printStackTrace();
}
} else
holder = (ViewHolder) v.getTag();
return v;
}
class ViewHolder {
TextView tv_group_name;
TextView tv_group_reg_id;
TextView tv_subscriber_count;
}
}
You are facing that data repeat issue, just because you aren't following the exact standards of implementing View-Holder pattern.
Wrong:
Here you are doing findViewById() and setting data if view is null, so it will be running fine for first set of items, afterword it will show you the same data for the next sets of items.
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v = convertView;
ViewHolder holder;
if (v == null) {
try {
LayoutInflater vi = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.group_item, null);
holder = new ViewHolder();
holder.tv_group_name = (TextView) v
.findViewById(R.id.tv_group_name);
String group_name = group_details.get(position).getGroup_name();
holder.tv_group_name.setText(group_name);
holder.tv_group_name.setTypeface(face);
holder.tv_group_reg_id = (TextView) v
.findViewById(R.id.tv_group_reg_id);
String groupRegId = group_details.get(position)
.getGroup_reg_id();
holder.tv_group_reg_id.setText(groupRegId);
holder.tv_group_reg_id.setTypeface(face);
holder.tv_subscriber_count = (TextView) v
.findViewById(R.id.tv_subscriber_count);
holder.tv_subscriber_count.setText(group_details.get(position)
.getSubscriber_count());
v.setTag(holder);
} catch (Exception e) {
e.printStackTrace();
}
} else
holder = (ViewHolder) v.getTag();
return v;
}
Correct:
Correct way to implement View Holder pattern is to find views if current view is null (that would happen for the first time) and set data only after doing it. So eventually findViewById() process will be done for the first time and next time onwards it will get views by using attached tags.
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v = convertView;
ViewHolder holder;
if (v == null) {
LayoutInflater vi = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.group_item, null);
holder = new ViewHolder();
holder.tv_group_name = (TextView) v
.findViewById(R.id.tv_group_name);
holder.tv_group_reg_id = (TextView) v
.findViewById(R.id.tv_group_reg_id);
holder.tv_subscriber_count = (TextView) v
.findViewById(R.id.tv_subscriber_count);
v.setTag(holder);
} catch (Exception e) {
e.printStackTrace();
}
} else
holder = (ViewHolder) v.getTag();
String group_name = group_details.get(position).getGroup_name();
holder.tv_group_name.setText(group_name);
holder.tv_group_name.setTypeface(face);
String groupRegId = group_details.get(position)
.getGroup_reg_id();
holder.tv_group_reg_id.setText(groupRegId);
holder.tv_group_reg_id.setTypeface(face);
holder.tv_subscriber_count.setText(group_details.get(position)
.getSubscriber_count());
return v;
}
You may get nullpointerexception.. to get rid out of this try this simple code
public View getView(int position, View convertView, ViewGroup parent) {
final ViewHolder vh;
View v = convertView;
if(v == null){
v = LayoutInflater.from(ctx).inflate(R.layout.simple_list_item, parent, false);
vh = new ViewHolder(v);
v.setTag(vh);
}
else{
vh = (ViewHolder) v.getTag();
}
vh.tvTitle.setText(list.get(position).toString());
return v;
}
class ViewHolder{
TextView tvTitle;
public ViewHolder(View v){
tvTitle = (TextView) v.findViewById(R.id.tvVideoName);
}
来源：https://stackoverflow.com/questions/23995052/repeating-items-in-listview