我很困惑點擊處理如何在這裏工作。爲什麼我們從主要活動this
到GreenAdapter
構造函數和設置ListItemClickListener mOnClickListener
到this
。回收站點擊處理是什麼?
在RecyclerView中的點擊處理工作到底如何。
NumberViewHolder僅在此處創建或調用10次,並可在100個項目視圖的其餘部分中循環使用。那麼onClick(View v)如何區分100個不同的列表項視圖。我們只在創建的10個項目視圖上設置itemView.setOnClickListener。
public class GreenAdapter extends RecyclerView.Adapter<GreenAdapter.NumberViewHolder> {
private static final String TAG = GreenAdapter.class.getSimpleName();
final private ListItemClickListener mOnClickListener;
private static int viewHolderCount;
private int mNumberItems;
public interface ListItemClickListener {
void onListItemClick(int clickedItemIndex);
}
public GreenAdapter(int numberOfItems, ListItemClickListener listener) {
mNumberItems = numberOfItems;
mOnClickListener = listener;
viewHolderCount = 0;
}
@Override
public NumberViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
Context context = viewGroup.getContext();
int layoutIdForListItem = R.layout.number_list_item;
LayoutInflater inflater = LayoutInflater.from(context);
boolean shouldAttachToParentImmediately = false;
View view = inflater.inflate(layoutIdForListItem, viewGroup, shouldAttachToParentImmediately);
NumberViewHolder viewHolder = new NumberViewHolder(view);
viewHolder.viewHolderIndex.setText("ViewHolder index: " + viewHolderCount);
int backgroundColorForViewHolder = ColorUtils
.getViewHolderBackgroundColorFromInstance(context, viewHolderCount);
viewHolder.itemView.setBackgroundColor(backgroundColorForViewHolder);
viewHolderCount++;
Log.d(TAG, "onCreateViewHolder: number of ViewHolders created: "
+ viewHolderCount);
return viewHolder;
}
@Override
public void onBindViewHolder(NumberViewHolder holder, int position) {
Log.d(TAG, "#" + position);
holder.bind(position);
}
@Override
public int getItemCount() {
return mNumberItems;
}
class NumberViewHolder extends RecyclerView.ViewHolder
implements View.OnClickListener {
// Will display the position in the list, ie 0 through getItemCount() - 1
TextView listItemNumberView;
// Will display which ViewHolder is displaying this data
TextView viewHolderIndex;
public NumberViewHolder(View itemView) {
super(itemView);
listItemNumberView = (TextView) itemView.findViewById(R.id.tv_item_number);
viewHolderIndex = (TextView) itemView.findViewById(R.id.tv_view_holder_instance);
itemView.setOnClickListener(this);
}
void bind(int listIndex) {
listItemNumberView.setText(String.valueOf(listIndex));
}
@Override
public void onClick(View v) {
int clickedPosition = getAdapterPosition();
mOnClickListener.onListItemClick(clickedPosition);
}
}
}
在mainActivity,我有
public class MainActivity extends AppCompatActivity
implements GreenAdapter.ListItemClickListener {
...
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNumbersList = (RecyclerView) findViewById(R.id.rv_numbers);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
mNumbersList.setLayoutManager(layoutManager);
mNumbersList.setHasFixedSize(true);
mAdapter = new GreenAdapter(NUM_LIST_ITEMS, this);
mNumbersList.setAdapter(mAdapter);
}
@Override
public void onListItemClick(int clickedItemIndex) {
if (mToast != null) {
mToast.cancel();
}
String toastMessage = "Item #" + clickedItemIndex + " clicked.";
mToast = Toast.makeText(this, toastMessage, Toast.LENGTH_LONG);
mToast.show();
}
...
}
這裏'this'關鍵字用來提實現的接口。實際上,它指的是一個MainActivity,它是一個ListItemClickListener。這是java的基礎知識。 –
好的,謝謝。 NumberViewHolder僅在此處創建或調用10次,並可在其餘項目視圖中循環使用。那麼onClick(View v)如何區分100個不同的列表項視圖 – raxx
爲什麼你要求我們解釋別人的代碼/你爲什麼不問問編寫它的人? –