我是firebase的新手。我正在尝试更新firebase数据库中的RecyclerView数据，同时动态反映我的RecyclerView数据中的相同更新值。即使有人试图从firebase控制台本身更新数据，更改也必须反映在recyclerView中。 我的列表中有一个seekBar，每次从列表中更改数据时，都必须反映在数据库中。问题是，每当我尝试从recyclerView列表本身更改数据时，firebase数据库中的数据都会发生变化，而firebase数据库又会调用onDataChanged（）并使其整个recyclelerView再次重新加载而不显示更新的数据列表。请帮忙。
Below I am posting my listfragment as well as adapter class code:
ListFragment:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v= inflater.inflate(R.layout.fragment_slc_list, container, false);
slcList = (RecyclerView)v.findViewById(R.id.addedSlcList);
noSLC = (TextView)v.findViewById(R.id.noSLCText);
fragmentManager= myContext.getSupportFragmentManager();
slcList.setHasFixedSize(true);
ref = new Firebase(Config.FIREBASE_URL);
list = new ArrayList<slcItem>();
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
// dAdapter = new slcListAdapter(myContext,list, ref );
// slcList.setLayoutManager(llm);
// slcList.setAdapter(dAdapter);
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot)
{
Log.d("clear","cleared");
list.clear();
for (DataSnapshot childDataSnapshot : dataSnapshot.getChildren()) {
Log.v("2nd",""+ childDataSnapshot.getKey()); //displays the key for the node
Log.v("2nd",""+ childDataSnapshot.getValue());
Slc val= childDataSnapshot.getValue(Slc.class);
Log.v("2ndClass",""+ val.getOn_off());
slcItem item = new slcItem();
item.setSlcOnOff(val.getOn_off());
item.setSlcID(val.getUser_id());
item.setSlcProgress(val.getDimming_val());
item.setSlcName(childDataSnapshot.getKey());
item.setSlcStatus(val.getStatus());
list.add(item);
LinearLayoutManager llm1 = new LinearLayoutManager(getActivity());
dAdapter = new slcListAdapter(myContext,list, ref );
dAdapter.notifyDataSetChanged();
slcList.setLayoutManager(llm1);
slcList.setAdapter(dAdapter);
}
for(int i=0; i<list.size();i++)
{
Log.d("animesh",list.get(i).getSlcName()+" "+list.size()+" "+dataSnapshot.getChildrenCount());
}
if(dataSnapshot.getChildrenCount() == 0)
{
LinearLayoutManager llm1 = new LinearLayoutManager(getActivity());
dAdapter = new slcListAdapter(myContext,list, ref );
getActivity().runOnUiThread(new Runnable() {
public void run() {
dAdapter.notifyDataSetChanged();
}
});
slcList.setLayoutManager(llm1);
slcList.setAdapter(dAdapter);
}
}
@Override
public void onCancelled(FirebaseError firebaseError)
{
Log.d("animesh",firebaseError+"");
}
});
Log.d("anilist",list.size()+"");
Adapter class:
public slcListAdapter(Context context,ArrayList<slcItem> list, Firebase ref ) {
super();
this.context=context;
this.list=list;
this.ref=ref;
dItems = new ArrayList<slcItem>();
for(int i=0;i<list.size();i++)
{
slcItem deal = new slcItem();
deal.setSlcName(list.get(i).getSlcName());
dItems.add(deal);
}
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.single_slc_row, viewGroup, false);
viewHolder = new ViewHolder(v);
return viewHolder;
}
@Override
public void onBindViewHolder(final ViewHolder viewHolder, final int i) {
int v;
nature = dItems.get(i);
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot)
{
for (DataSnapshot childDataSnapshot : dataSnapshot.getChildren())
{
Log.d("animesh",childDataSnapshot.toString());
Slc val = childDataSnapshot.getValue(Slc.class);
// viewHolder.dimming.setProgress(val.getDimming_val());
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
});
viewHolder.name.setText(nature.getSlcName());
viewHolder.inv.setVisibility(View.GONE);
viewHolder.onOff.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
Log.d("checkani",nature.getSlcName());
if(isChecked){
ref.child(list.get(i).getSlcName()).child("on_off").setValue(1);
}else{
ref.child(list.get(i).getSlcName()).child("on_off").setValue(0);
Log.d("Ani",list.get(i).getSlcName());
}
}
});
viewHolder.dimming.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener()
{
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser)
{
Log.d("dimming",nature.getSlcName());
ref.child(list.get(i).getSlcName()).child("dimming_val").setValue(progress);
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
viewHolder.expand.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
// ViewAnimationsUtils.expand(viewHolder.inv);
viewHolder.collapse.setVisibility(View.VISIBLE);
viewHolder.inv.setVisibility(View.VISIBLE);
viewHolder.expand.setVisibility(View.GONE);
}
});
viewHolder.collapse.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
// ViewAnimationsUtils.collapse(inv);
viewHolder.inv.setVisibility(View.GONE);
viewHolder.expand.setVisibility(View.VISIBLE);
viewHolder.collapse.setVisibility(View.GONE);
}
});
viewHolder.edit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
final Dialog dialog = new Dialog(context);
dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
dialog.setContentView(R.layout.update_slc);
dialog.setCancelable(false);
Window window = dialog.getWindow();
if(window == null) return;
WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
lp.copyFrom(dialog.getWindow().getAttributes());
lp.width = WindowManager.LayoutParams.MATCH_PARENT;
lp.height = WindowManager.LayoutParams.WRAP_CONTENT;
lp.gravity = Gravity.CENTER;
dialog.getWindow().setAttributes(lp);
final EditText name = (EditText) dialog.findViewById(R.id.slcNameu);
final EditText id = (EditText) dialog.findViewById(R.id.slcIDu);
TextView cancel = (TextView) dialog.findViewById(R.id.cancelu);
TextView update = (TextView) dialog.findViewById(R.id.updateSlc);
// update.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View v)
// {
// final String Sname = nature.getSlcName();
// Map mParent = new HashMap();
// mParent.put("user_id", id.getText().toString().trim());
// mParent.put("on_off", nature.getSlcOnOff());
// mParent.put("status", nature.getSlcStatus());
// mParent.put("dimming_val",nature.getSlcProgress());
// ref.child(name.getText().toString().trim()).setValue(mParent, new Firebase.CompletionListener()
// {
// @Override
// public void onComplete(FirebaseError firebaseError, Firebase firebase) {
// Log.d("aniNature","Value was set. Error = "+firebaseError+" "+nature.getSlcName()+" "+Sname);
// ref.child(Sname).removeValue();
// dialog.dismiss();
// }
// });
//
// }
// });
cancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});
dialog.show();
}
});
viewHolder.delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
final Dialog dialog = new Dialog(context);
dialog.setTitle("Delete Slc?");
dialog.setContentView(R.layout.delete_slc);
dialog.setCancelable(false);
Window window = dialog.getWindow();
if(window == null) return;
WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
lp.copyFrom(dialog.getWindow().getAttributes());
lp.width = WindowManager.LayoutParams.MATCH_PARENT;
lp.height = WindowManager.LayoutParams.WRAP_CONTENT;
lp.gravity = Gravity.CENTER;
dialog.getWindow().setAttributes(lp);
TextView delete = (TextView)dialog.findViewById(R.id.deleteSlc);
delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
Log.d("delete1",nature.getSlcName());
ref.child(list.get(i).getSlcName()).removeValue();
Log.d("delete",nature.getSlcName());
dialog.dismiss();
}
});
TextView dialogButton = (TextView) dialog.findViewById(R.id.canceld);
// if button is clicked, close the custom dialog
dialogButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
dialog.dismiss();
}
});
dialog.show();
}
});
}
@Override
public int getItemCount()
{
return dItems.size();
}
class ViewHolder extends RecyclerView.ViewHolder{
public TextView name;
public Switch onOff;
public SeekBar dimming;
public TextView edit;
public TextView delete;
public TextView expand;
public TextView collapse;
public LinearLayout inv;
public ViewHolder(View itemView)
{
super(itemView);
name = (TextView) itemView.findViewById(R.id.slcName);
onOff = (Switch) itemView.findViewById(R.id.slcONOFFSwich);
dimming=(SeekBar) itemView.findViewById(R.id.slcDimming);
edit = (TextView) itemView.findViewById(R.id.EditSlc);
delete = (TextView) itemView.findViewById(R.id.DeleteSlc);
expand = (TextView) itemView.findViewById(R.id.down);
collapse = (TextView) itemView.findViewById(R.id.up);
inv = (LinearLayout) itemView.findViewById(R.id.invisibleLayout);
}
}
}
答案 0 :(得分：1)
如果您想要回复儿童级别的更改，则应使用ChildEventListener。此界面具有单独的方法，用于在添加，删除，更改或移动子项时（分别为onChildAdded，onChildRemoved，onChildChanged和onChildMoved）。
请注意，您需要在此方案中执行更多工作，以确保项目在list中保持正确的顺序。例如：您需要跟踪每个项目的关键字，以便将其与previousKey和onChildAdded中的onChildChanged参数进行比较。
有关此类适配器的工作实现的示例，我建议您查看FirebaseUI的FirebaseRecyclerAdapter及其基础FirebaseArray。
答案 1 :(得分：1)
您需要在侦听器中更改此内容：
LinearLayoutManager llm1 = new LinearLayoutManager(getActivity());
dAdapter = new slcListAdapter(myContext,list, ref );
dAdapter.notifyDataSetChanged();
slcList.setLayoutManager(llm1);
slcList.setAdapter(dAdapter);
每次数据更改时都会设置新的适配器。您必须维护列表并跟踪该列表。每次更改项目时，只需在列表中对其进行编辑，并仅通知这些更改。
无需每次都创建新的适配器
答案 2 :(得分：0)
而不是使用addValueEventListener使用addListenerForSingleValueEvent，这只会从Firebase获取一次数据，而不会监听更新。
检查this website for detailed documentation
一次读取数据
在某些情况下，调用一次然后立即删除回调可能很有用。我们已经创建了一个辅助函数来简化：
ref.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
// ...
}
@Override
public void onCancelled(DatabaseError databaseError) {
// ...
}
});