CODEWITHSUNDEEP
androidlistviewandroid-listviewandroid-arrayadapterfindviewbyid
Marian Paździoch
Marian Paździoch

Reputation: 9093

How to check if a view is of an appropriate type before using in Adapter getView

I'm using Adapter with 3 types of Views

public class MyAdapter extends ArrayAdapter<MyClass> {
    @Override
    public int getViewTypeCount() {
        return 3;
    }

    //...
}

And it appears that sometimes wrong types of Views are passed to getView. Indeed docs warn about it:

Note: You should check that this view is non-null and of an appropriate type before using.

How should I check if a view is of an appropriate type before using?

Should I just check by findViewById if it contains some id from appropriate xml? But does it really check "if a view is of an appropriate type"?

EDIT: Answers so far seems to not miss my question so to clarify: Yeah I'm using getItemViewType but as I have 3 types of Views, then sometimes convertView in getView has wrong type (not the View which was inflated for the getItemViewType) and cannot be converted to the right one - the question is not about how to check which View SHOULD be returned (and this is covered by "bigdestroyer" answer), but if the View passed to getView can be reused (and in my case it cannot).

Upvotes: 1

Views: 777

Answers (2)

H&#233;ctor
H&#233;ctor

Reputation: 26034

"Appropriate type" means that you have to check in getView method the type of the convertView in order to return a custom View or another one.

You can override getItemViewType method of BaseAdapter. For instance:

public int getItemViewType(int position) {

      MyItem item = getItem(position);
      return item.getViewType();

}

and:

public View getView(int position, View convertView, ViewGroup parent) {

     int viewType = getItemViewType(position);

     if (convertView != null) {

         if (viewType == 1) return recycleViewOfType1(position, convertView);
         if (viewType == 2) return recycleViewOfType2(position, convertView);

     }

     else {

         if (viewType == 1) return newViewOfType1(position);
         if (viewType == 2) return newViewOfType2(position);

     }

         return null;         
}

Upvotes: 2

Prachi
Prachi

Reputation: 2559

You can use getItemViewType() method to determine view type before creating/ reusing views in getView() method. 

@Override
public View getView(int position, View convertView, ViewGroup parent) {
int type = getItemViewType(position);

if(type == 1){

}else {

}
}

check this tutorial for more info

Upvotes: 0

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