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A helper class for Android ArrayAdapters
package audio.rabid.dev.utils;
import android.content.Context;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import java.util.ArrayList;
import java.util.List;
/**
* I got tired of building the same ArrayAdapter over and over.
*
* Subclass this class with two generics: {@link T} is the class of the "Model" object
* and {@link V} is the class of the "View" object. Typically, you'll want to make a protected
* ViewHolder subclass. If you do that, {@link #createViewHolder(View)} becomes as simple as
*
* <pre>
* @Override
* protected ViewHolder createViewHolder(View v) {
* return new ViewHolder(v);
* }
* </pre>
*
* The other method you need is {@link #onDrawView(Object, Object)} which gives you the model and the
* ViewHolder and allows you to map the data to the view.
*
* Everything else is handled for you (all the inflation bullshit, keeping track of the collection, etc.).
*
* @author Charles Julian Knight, <a href="mailto:charles@rabidaudio.com">charles@rabidaudio.com</a>
*
* @see <a href="http://developer.android.com/training/improving-layouts/smooth-scrolling.html">ViewHolder Pattern</a>
*/
public abstract class EasyArrayAdapter<T, V> extends ArrayAdapter<T> {
private Context context;
private int layoutId;
private List<T> list;
/**
*
* @param context the parent context
* @param layoutId the ID of the layout resource to use as the view for each item
* @param list the collection of backing objects
*/
public EasyArrayAdapter(Context context, int layoutId, @Nullable List<T> list){
super(context, layoutId, (list==null ? new ArrayList<T>() : list));
this.context = context;
this.layoutId = layoutId;
this.list = list;
}
protected abstract void onDrawView(T object, V viewHolder, View parent);
protected abstract V createViewHolder(View v);
public List<T> getCollection(){
return list;
}
@SuppressWarnings("unchecked")
@Override
public View getView(int position, View view, ViewGroup viewGroup) {
LayoutInflater inflater = LayoutInflater.from(context);
View rowView;
V viewHolder;
if (view == null) {
rowView = inflater.inflate(layoutId, viewGroup, false);
viewHolder = createViewHolder(rowView);
rowView.setTag(viewHolder);
} else {
rowView = view;
viewHolder = (V) rowView.getTag();
if (viewHolder == null) {
//for some reason, no holder attached
viewHolder = createViewHolder(rowView);
rowView.setTag(viewHolder);
}
}
onDrawView(list.get(position), viewHolder, rowView);
return rowView;
}
}
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