列表项中的每个操作都是从RecyclerView.ViewHolder处理的。实际上，我想在FirebaseRecyclerAdapter中将Activity上下文传递给ViewHolder，所以我尝试将Constructor添加到此ViewHolder中，如下所示：
public class TodoViewHolder extends RecyclerView.ViewHolder {
@BindView(R.id.accbListItemHome)
AppCompatCheckBox mAppCompatCheckBox;
@BindView(R.id.actvListItemHome)
AppCompatTextView mAppCompatTextView;
@BindView(R.id.acibListItemHome)
AppCompatImageButton mAppCompatImageButton;
private Context mContext;
public TodoViewHolder(Context context, View itemView) {
super(itemView);
mContext = context;
ButterKnife.bind(this, itemView);
}
public AppCompatCheckBox getmAppCompatCheckBox() {
return mAppCompatCheckBox;
}
public AppCompatTextView getmAppCompatTextView() {
return mAppCompatTextView;
}
public AppCompatImageButton getmAppCompatImageButton() {
return mAppCompatImageButton;
}
@OnCheckedChanged(R.id.accbListItemHome)
void onCheckBoxChange(CompoundButton compoundButton, boolean checked) {
TodoMasterModel todoMasterModel = (TodoMasterModel) compoundButton.getTag();
todoMasterModel.getmTodoModel().setmIsCompleted(checked);
((HomeActivity) mContext).onDoneClick(todoMasterModel, AddEditDialogFragment.ACTION_Edit);
Log.i("Checkbox", todoMasterModel.toString());
}
@OnClick(R.id.actvListItemHome)
void onTextViewClick(View view) {
TodoMasterModel todoMasterModel = (TodoMasterModel) view.getTag();
((HomeActivity) mContext).showAddEditDialog(todoMasterModel, AddEditDialogFragment.ACTION_Edit);
Log.i("TextView", todoMasterModel.toString());
}
@OnClick(R.id.acibListItemHome)
void onImageButtonClick(View view) {
TodoMasterModel todoMasterModel = (TodoMasterModel) view.getTag();
FirebaseDatabase.getInstance().getReference("todos").child(todoMasterModel.getmId()).setValue(todoMasterModel.getmTodoModel());
Log.i("Delete", todoMasterModel.toString());
}
}
我为我的目的创建了我的课程并修改了FirebaseRecyclerAdapter，如下所示：
public abstract class MyFirebaseAdapter<T, VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {
private Context mContext;
protected int mModelLayout;
Class<T> mModelClass;
Class<VH> mViewHolderClass;
FirebaseArray mSnapshots;
/**
* @param modelClass Firebase will marshall the data at a location into an instance of a class that you provide
* @param modelLayout This is the layout used to represent a single item in the list. You will be responsible for populating an
* instance of the corresponding view with the data from an instance of modelClass.
* @param viewHolderClass The class that hold references to all sub-views in an instance modelLayout.
* @param ref The Firebase location to watch for data changes. Can also be a slice of a location, using some
* combination of <code>limit()</code>, <code>startAt()</code>, and <code>endAt()</code>
*/
public MyFirebaseAdapter(Context context, Class<T> modelClass, int modelLayout, Class<VH> viewHolderClass, Query ref) {
mContext = context;
mModelClass = modelClass;
mModelLayout = modelLayout;
mViewHolderClass = viewHolderClass;
mSnapshots = new FirebaseArray(ref);
mSnapshots.setOnChangedListener(new FirebaseArray.OnChangedListener() {
@Override
public void onChanged(EventType type, int index, int oldIndex) {
switch (type) {
case Added:
notifyItemInserted(index);
break;
case Changed:
notifyItemChanged(index);
break;
case Removed:
notifyItemRemoved(index);
break;
case Moved:
notifyItemMoved(oldIndex, index);
break;
default:
throw new IllegalStateException("Incomplete case statement");
}
}
});
}
/**
* @param modelClass Firebase will marshall the data at a location into an instance of a class that you provide
* @param modelLayout This is the layout used to represent a single item in the list. You will be responsible for populating an
* instance of the corresponding view with the data from an instance of modelClass.
* @param viewHolderClass The class that hold references to all sub-views in an instance modelLayout.
* @param ref The Firebase location to watch for data changes. Can also be a slice of a location, using some
* combination of <code>limit()</code>, <code>startAt()</code>, and <code>endAt()</code>
*/
public MyFirebaseAdapter(Context context, Class<T> modelClass, int modelLayout, Class<VH> viewHolderClass, DatabaseReference ref) {
this(context, modelClass, modelLayout, viewHolderClass, (Query) ref);
}
public void cleanup() {
mSnapshots.cleanup();
}
@Override
public int getItemCount() {
return mSnapshots.getCount();
}
public T getItem(int position) {
return parseSnapshot(mSnapshots.getItem(position));
}
/**
* This method parses the DataSnapshot into the requested type. You can override it in subclasses
* to do custom parsing.
*
* @param snapshot the DataSnapshot to extract the model from
* @return the model extracted from the DataSnapshot
*/
protected T parseSnapshot(DataSnapshot snapshot) {
return snapshot.getValue(mModelClass);
}
public DatabaseReference getRef(int position) {
return mSnapshots.getItem(position).getRef();
}
@Override
public long getItemId(int position) {
// http://stackoverflow.com/questions/5100071/whats-the-purpose-of-item-ids-in-android-listview-adapter
return mSnapshots.getItem(position).getKey().hashCode();
}
@Override
public VH onCreateViewHolder(ViewGroup parent, int viewType) {
ViewGroup view = (ViewGroup) LayoutInflater.from(parent.getContext()).inflate(viewType, parent, false);
try {
Constructor<VH> constructor = mViewHolderClass.getConstructor(View.class);
return constructor.newInstance(mContext, view);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
} catch (InstantiationException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
}
@Override
public void onBindViewHolder(VH viewHolder, int position) {
T model = getItem(position);
populateViewHolder(viewHolder, model, position);
}
@Override
public int getItemViewType(int position) {
return mModelLayout;
}
/**
* Each time the data at the given Firebase location changes, this method will be called for each item that needs
* to be displayed. The first two arguments correspond to the mLayout and mModelClass given to the constructor of
* this class. The third argument is the item's position in the list.
* <p>
* Your implementation should populate the view using the data contained in the model.
*
* @param viewHolder The view to populate
* @param model The object containing the data used to populate the view
* @param position The position in the list of the view being populated
*/
abstract protected void populateViewHolder(VH viewHolder, T model, int position);
}
由于这一行错误即将到来：
return constructor.newInstance(mContext, view);
但我得到NoSuchMethod异常。我知道我做错了。但我没有办法做到这一点。任何人都可以帮我吗？
java.lang.RuntimeException：java.lang.NoSuchMethodException： [类android.view.View] 在 com.letsnurture.android.firebasedatabasedemo.adapter.MyFirebaseAdapter.onCreateViewHolder（MyFirebaseAdapter.java:120） 在 android.support.v7.widget.RecyclerView $ Adapter.createViewHolder（RecyclerView.java:5779） 在 android.support.v7.widget.RecyclerView $ Recycler.getViewForPosition（RecyclerView.java:5003） 在 android.support.v7.widget.RecyclerView $ Recycler.getViewForPosition（RecyclerView.java:4913） 在 android.support.v7.widget.LinearLayoutManager $ LayoutState.next（LinearLayoutManager.java:2029） 在 android.support.v7.widget.LinearLayoutManager.layoutChunk（LinearLayoutManager.java:1414） 在 android.support.v7.widget.LinearLayoutManager.fill（LinearLayoutManager.java:1377） 在 android.support.v7.widget.LinearLayoutManager.onLayoutChildren（LinearLayoutManager.java:578） 在 android.support.v7.widget.RecyclerView.dispatchLayoutStep2（RecyclerView.java:3260） 在 android.support.v7.widget.RecyclerView.dispatchLayout（RecyclerView.java:3069） 在 android.support.v7.widget.RecyclerView.onLayout（RecyclerView.java:3518） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.widget.LinearLayout.setChildFrame（LinearLayout.java:1743） 在 android.widget.LinearLayout.layoutHorizontal（LinearLayout.java:1732） 在android.widget.LinearLayout.onLayout（LinearLayout.java:1497） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在 android.support.design.widget.HeaderScrollingViewBehavior.layoutChild（HeaderScrollingViewBehavior.java:120） 在 android.support.design.widget.ViewOffsetBehavior.onLayoutChild（ViewOffsetBehavior.java:42） 在 android.support.design.widget.AppBarLayout $ ScrollingViewBehavior.onLayoutChild（AppBarLayout.java:1319） 在 android.support.design.widget.CoordinatorLayout.onLayout（CoordinatorLayout.java:815） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在 android.support.v4.widget.DrawerLayout.onLayout（DrawerLayout.java:1191） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.widget.FrameLayout.layoutChildren（FrameLayout.java:336） 在android.widget.FrameLayout.onLayout（FrameLayout.java:273） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.widget.LinearLayout.setChildFrame（LinearLayout.java:1743） 在android.widget.LinearLayout.layoutVertical（LinearLayout.java:1586） 在android.widget.LinearLayout.onLayout（LinearLayout.java:1495） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.widget.FrameLayout.layoutChildren（FrameLayout.java:336） 在android.widget.FrameLayout.onLayout（FrameLayout.java:273） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.widget.LinearLayout.setChildFrame（LinearLayout.java:1743） 在android.widget.LinearLayout.layoutVertical（LinearLayout.java:1586） 在android.widget.LinearLayout.onLayout（LinearLayout.java:1495） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.widget.FrameLayout.layoutChildren（FrameLayout.java:336） 在android.widget.FrameLayout.onLayout（FrameLayout.java:273） 在 com.android.internal.policy.PhoneWindow $ DecorView.onLayout（PhoneWindow.java:2678） 在android.view.View.layout（View.java:16651） 在android.view.ViewGroup.layout（ViewGroup.java:5440） 在android.view.ViewRootImpl.performLayout（ViewRootImpl.java:2183） 在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1943） 在android.view.ViewRootImpl.doTraversal（ViewRootImpl.java:1119） 在 android.view.ViewRootImpl $ TraversalRunnable.run（ViewRootImpl.java:6060） 在 android.view.Choreographer $ CallbackRecord.run（Choreographer.java:858） 在android.vi
答案 0 :(得分：3)
您的ViewHolder子类需要一个只有View参数的构造函数。来自FirebaseUI documentation：
public static class ChatHolder extends RecyclerView.ViewHolder {
View mView;
public ChatHolder(View itemView) {
super(itemView);
mView = itemView;
}
原因在于this code，它只搜索单个签名。添加代码以搜索ViewHolder(Context, View)构造函数可能是一个很好的补充。您可以为FirebaseUI github repo添加功能请求吗？
更新：feature request on Github为那些想要+1的人。 ： - ）
答案 1 :(得分：0)
将Activity上下文传递给Adapter并不总是正确的做事方式。您应该创建一个Activity实现的接口，并将其传递给您的Adapter。 另一种流行的方法是使用pubsub模式来引发事件，并在EventBus等库发生某些事件时订阅它们。
答案 2 :(得分：0)
解决方案：
我创建了一个界面OnTodoActionListener.java，如下所示：
public interface OnTodoActionListener {
void onCheckBoxChange(CompoundButton compoundButton, boolean checked);
void onTextViewClick(View view);
void onImageButtonClick(View view);
}
然后，我在Activity中创建了这个接口的对象：
private OnTodoActionListener mOnTodoActionListener;
mOnTodoActionListener = new OnTodoActionListener() {
@Override
public void onCheckBoxChange(CompoundButton compoundButton, boolean checked) {
TodoMasterModel todoMasterModel = (TodoMasterModel) compoundButton.getTag();
todoMasterModel.getmTodoModel().setmIsCompleted(checked);
onDoneClick(todoMasterModel, AddEditDialogFragment.ACTION_Edit);
Log.i("Checkbox", todoMasterModel.toString());
}
@Override
public void onTextViewClick(View view) {
TodoMasterModel todoMasterModel = (TodoMasterModel) view.getTag();
showAddEditDialog(todoMasterModel, AddEditDialogFragment.ACTION_Edit);
Log.i("TextView", todoMasterModel.toString());
}
@Override
public void onImageButtonClick(View view) {
TodoMasterModel todoMasterModel = (TodoMasterModel) view.getTag();
mDatabaseReferenceTodo.child(todoMasterModel.getmId()).setValue(null);
Log.i("Delete", todoMasterModel.toString());
}
};
我在我的TodoViewHolder中创建了一个setter方法，并使用了如下引用：
private OnTodoActionListener mOnTodoActionListener;
public void setListener(OnTodoActionListener onTodoActionListener) {
mOnTodoActionListener = onTodoActionListener;
}
@OnCheckedChanged(R.id.accbListItemHome)
void onCheckBoxChange(CompoundButton compoundButton, boolean checked) {
mOnTodoActionListener.onCheckBoxChange(compoundButton, checked);
}
@OnClick(R.id.actvListItemHome)
void onTextViewClick(View view) {
mOnTodoActionListener.onTextViewClick(view);
}
@OnClick(R.id.acibListItemHome)
void onImageButtonClick(View view) {
mOnTodoActionListener.onImageButtonClick(view);
}
最后，我将在Activity中创建的侦听器设置为：
FirebaseRecyclerAdapter mHomeRecyclerAdapter = new FirebaseRecyclerAdapter<TodoModel, TodoViewHolder>(TodoModel.class, R.layout.list_item_home, TodoViewHolder.class, mDatabaseReferenceTodo) {
@Override
public void populateViewHolder(TodoViewHolder todoViewHolder, TodoModel todoModel, int position) {
todoViewHolder.setListener(mOnTodoActionListener);
TodoMasterModel todoMasterModel = new TodoMasterModel(getRef(position).getKey(), todoModel);
todoViewHolder.getmAppCompatCheckBox().setTag(todoMasterModel);
todoViewHolder.getmAppCompatTextView().setTag(todoMasterModel);
todoViewHolder.getmAppCompatImageButton().setTag(todoMasterModel);
todoViewHolder.getmAppCompatCheckBox().setChecked(todoModel.ismIsCompleted());
todoViewHolder.getmAppCompatTextView().setText(todoModel.getmTodoContent());
}
};
mRecyclerView.setAdapter(mHomeRecyclerAdapter);
最后，我现在能够创建一个完整工作的演示＆＃34; Todo App＆＃34;使用Firebase实时数据库。我上传后会将链接发布到Github。感谢。
更新：您可以使用firebase数据库创建我的Todo App演示。这是链接：Firebase Database Demo