Handle Button click inside a row in RecyclerView
I wanted a solution that did not create any extra objects (ie listeners) that would have to be garbage collected later, and did not require nesting a view holder inside an adapter class.
In the ViewHolder class
private static class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
private final TextView ....// declare the fields in your view
private ClickHandler ClickHandler;
public MyHolder(final View itemView) {
super(itemView);
nameField = (TextView) itemView.findViewById(R.id.name);
//find other fields here...
Button myButton = (Button) itemView.findViewById(R.id.my_button);
myButton.setOnClickListener(this);
}
...
@Override
public void onClick(final View view) {
if (clickHandler != null) {
clickHandler.onMyButtonClicked(getAdapterPosition());
}
}
Points to note: the ClickHandler interface is defined, but not initialized here, so there is no assumption in the onClick method that it was ever initialized.
The ClickHandler interface looks like this:
private interface ClickHandler {
void onMyButtonClicked(final int position);
}
In the adapter, set an instance of 'ClickHandler' in the constructor, and override onBindViewHolder, to initialize `clickHandler' on the view holder:
private class MyAdapter extends ...{
private final ClickHandler clickHandler;
public MyAdapter(final ClickHandler clickHandler) {
super(...);
this.clickHandler = clickHandler;
}
@Override
public void onBindViewHolder(final MyViewHolder viewHolder, final int position) {
super.onBindViewHolder(viewHolder, position);
viewHolder.clickHandler = this.clickHandler;
}
Note: I know that viewHolder.clickHandler is potentially getting set multiple times with the exact same value, but this is cheaper than checking for null and branching, and there is no memory cost, just an extra instruction.
Finally, when you create the adapter, you are forced to pass a ClickHandlerinstance to the constructor, as so:
adapter = new MyAdapter(new ClickHandler() {
@Override
public void onMyButtonClicked(final int position) {
final MyModel model = adapter.getItem(position);
//do something with the model where the button was clicked
}
});
Note that adapter is a member variable here, not a local variable
this is how I handle multiple onClick events inside a recyclerView:
Edit : Updated to include callbacks (as mentioned in other comments). I have used a WeakReference in the ViewHolder to eliminate a potential memory leak.
Define interface :
public interface ClickListener {
void onPositionClicked(int position);
void onLongClicked(int position);
}
Then the Adapter :
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
private final ClickListener listener;
private final List<MyItems> itemsList;
public MyAdapter(List<MyItems> itemsList, ClickListener listener) {
this.listener = listener;
this.itemsList = itemsList;
}
@Override public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new MyViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.my_row_layout), parent, false), listener);
}
@Override public void onBindViewHolder(MyViewHolder holder, int position) {
// bind layout and data etc..
}
@Override public int getItemCount() {
return itemsList.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
private ImageView iconImageView;
private TextView iconTextView;
private WeakReference<ClickListener> listenerRef;
public MyViewHolder(final View itemView, ClickListener listener) {
super(itemView);
listenerRef = new WeakReference<>(listener);
iconImageView = (ImageView) itemView.findViewById(R.id.myRecyclerImageView);
iconTextView = (TextView) itemView.findViewById(R.id.myRecyclerTextView);
itemView.setOnClickListener(this);
iconTextView.setOnClickListener(this);
iconImageView.setOnLongClickListener(this);
}
// onClick Listener for view
@Override
public void onClick(View v) {
if (v.getId() == iconTextView.getId()) {
Toast.makeText(v.getContext(), "ITEM PRESSED = " + String.valueOf(getAdapterPosition()), Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(v.getContext(), "ROW PRESSED = " + String.valueOf(getAdapterPosition()), Toast.LENGTH_SHORT).show();
}
listenerRef.get().onPositionClicked(getAdapterPosition());
}
//onLongClickListener for view
@Override
public boolean onLongClick(View v) {
final AlertDialog.Builder builder = new AlertDialog.Builder(v.getContext());
builder.setTitle("Hello Dialog")
.setMessage("LONG CLICK DIALOG WINDOW FOR ICON " + String.valueOf(getAdapterPosition()))
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
builder.create().show();
listenerRef.get().onLongClicked(getAdapterPosition());
return true;
}
}
}
Then in your activity/fragment - whatever you can implement : Clicklistener - or anonymous class if you wish like so :
MyAdapter adapter = new MyAdapter(myItems, new ClickListener() {
@Override public void onPositionClicked(int position) {
// callback performed on click
}
@Override public void onLongClicked(int position) {
// callback performed on click
}
});
To get which item was clicked you match the view id i.e. v.getId() == whateverItem.getId()
Hope this approach helps!
I find that typically:
- I need to use multiple listeners because I have several buttons.
- I want my logic to be in the activity and not the adapter or viewholder.
So @mark-keen's answer works well but having an interface provides more flexibility:
public static class MyViewHolder extends RecyclerView.ViewHolder {
public ImageView iconImageView;
public TextView iconTextView;
public MyViewHolder(final View itemView) {
super(itemView);
iconImageView = (ImageView) itemView.findViewById(R.id.myRecyclerImageView);
iconTextView = (TextView) itemView.findViewById(R.id.myRecyclerTextView);
iconTextView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onClickListener.iconTextViewOnClick(v, getAdapterPosition());
}
});
iconImageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onClickListener.iconImageViewOnClick(v, getAdapterPosition());
}
});
}
}
Where onClickListener is defined in your adapter:
public MyAdapterListener onClickListener;
public interface MyAdapterListener {
void iconTextViewOnClick(View v, int position);
void iconImageViewOnClick(View v, int position);
}
And probably set through your constructor:
public MyAdapter(ArrayList<MyListItems> newRows, MyAdapterListener listener) {
rows = newRows;
onClickListener = listener;
}
Then you can handle the events in your Activity or wherever your RecyclerView is being used:
mAdapter = new MyAdapter(mRows, new MyAdapter.MyAdapterListener() {
@Override
public void iconTextViewOnClick(View v, int position) {
Log.d(TAG, "iconTextViewOnClick at position "+position);
}
@Override
public void iconImageViewOnClick(View v, int position) {
Log.d(TAG, "iconImageViewOnClick at position "+position);
}
});
mRecycler.setAdapter(mAdapter);