分析查询后RecyclerView notifyDataSetChanged不工作 [英] RecyclerView notifyDataSetChanged not working after Parse query
本文介绍了分析查询后RecyclerView notifyDataSetChanged不工作的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在尝试更新了我的看法回收片段，解析查询一些数据之后。在查询我称之为 notifyDataSetChagned 的完成方法，但该列表永远不会显示
包com.garciaericn.t2d.fragments;
公共类DevicesCardViewFragment扩展片段实现View.OnClickListener { 私人OnFragmentInteractionListener mListener;
私人BatteryHelper mBatteryHelper;
意图mBatteryStatus; 私人RecyclerView mRecyclerView;
私人DeviceAdapter mAdapter;
私人RecyclerView.LayoutManager mLayoutManager;
私人列表＆LT;装置＆gt; mDevices; 公共DevicesCardViewFragment（）{
//必需的空公共构造
mDevices =新的ArrayList＆LT;装置＆gt;（）;
} 公共静态的newInstance DevicesCardViewFragment（）{
//捆绑参数是必要的 返回新DevicesCardViewFragment（）;
} @覆盖
公共无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
//获取参数
getDevices（）; mBatteryHelper =新BatteryHelper（getActivity（））; IntentFilter的IntentFilter的=新的IntentFilter（Intent.ACTION_BATTERY_CHANGED）;
mBatteryStatus = getActivity（）registerReceiver（NULL，IntentFilter的）。 //当前设备的更新统计信息。 Toast.makeText（getActivity（），电池电量：+ mBatteryHelper.getCurrentBatteryLevel（）+％，Toast.LENGTH_LONG）.show（）; //更新设备统计 } @覆盖
公共查看onCreateView（LayoutInflater充气器，容器的ViewGroup，捆绑savedInstanceState）{
查看查看= inflater.inflate（R.layout.fragment_devices_list，集装箱，FALSE）; mListener.showAd（）; //获取回收视图
mRecyclerView =（RecyclerView）view.findViewById（R.id.devices_recycler_view）;
mRecyclerView.setHasFixedSize（真）; mAdapter =新DeviceAdapter（getActivity（），mDevices）; //设置适配器
mRecyclerView.setAdapter（mAdapter）; //设置布局管理器
mLayoutManager =新LinearLayoutManager（getActivity（））;
mRecyclerView.setLayoutManager（mLayoutManager）;
返回视图。
} @覆盖
公共无效onAttach（活动活动）{
super.onAttach（活动）;
尝试{
mListener =（OnFragmentInteractionListener）活性;
}赶上（抛出ClassCastException E）{
抛出新ClassCastException异常（activity.toString（）
+必须实现OnFragmentInteractionListener）;
}
} @覆盖
公共无效onDetach（）{
super.onDetach（）;
mListener = NULL;
} 公开名单＆LT;装置＆gt; getDevices（）{ ParseQuery＆所述;装置＆gt;查询= ParseQuery.getQuery（Device.DEVICES）;
//新ParseQuery＆LT;装置＆gt;（Device.DEVICES）;
query.whereEqualTo（deviceUser，ParseUser.getCurrentUser（））;
query.findInBackground（新FindCallback＆所述;装置＆gt;（）{
@覆盖
公共无效完成（列表＆LT;装置＆gt;装置，ParseException的E）{
如果（E == NULL）{
//循环回装置
对于（设备设备：设备）{
设备currentDevice =新的设备（）;
currentDevice.setDeviceName（device.getDeviceName（））;
currentDevice.setBatteryLevel（device.getBatteryLevel（））;
currentDevice.setIsCharging（device.isCharging（））;
mDevices.add（currentDevice）;
}
mAdapter.notifyDataSetChanged（）;
}其他{
// 出了些问题
Toast.makeText（getActivity（），错误：+ e.toString（），Toast.LENGTH_LONG）.show（）;
}
}
}）; 返回mDevices;
} @覆盖
公共无效的onClick（视图v）{
// Click事件何去何从
} 公共静态的newInstance DevicesCardViewFragment（列表＆LT;装置＆gt; mDevices）{
DevicesCardViewFragment片段=新DevicesCardViewFragment（）; 捆绑ARGS =新包（）; 返回片段;
} 公共接口OnFragmentInteractionListener {
公共无效showAd（）;
}
}
我recyclerViewAdapter看起来像这样...
包com.garciaericn.t2d.data;公共类DeviceAdapter扩展RecyclerView.Adapter＆LT; DeviceAdapter.MyViewHolder＆GT; { 私人最终LayoutInflater吹气; 清单＆LT;装置＆gt;数据= Collections.emptyList（）; 公共DeviceAdapter（上下文的背景下，列表与LT;装置＆gt;数据）{
充气= LayoutInflater.from（上下文）;
this.data =数据;
} @覆盖 公共MyViewHolder onCreateViewHolder（ViewGroup中的父母，INT viewType）{
查看查看= inflater.inflate（R.layout.card_layout，父母，假）; MyViewHolder持有人=新MyViewHolder（视图）; 回到持有人;
} @覆盖
公共无效onBindViewHolder（MyViewHolder持有人，INT位置）{ 设备device = data.get（位置）; holder.deviceNameTV.setText（device.getDeviceName（））;
holder.batteryLevelTV.setText（device.getBatteryLevel（））;
} @覆盖
公众诠释getItemCount（）{
返回0;
} 公共静态类MyViewHolder扩展RecyclerView.ViewHolder {
//临时数据集
私有String [] mDataset; TextView的deviceNameTV;
TextView的batteryLevelTV; 公共MyViewHolder（查看ItemView控件）{
超（ItemView控件）;
deviceNameTV =（TextView中）itemView.findViewById（R.id.device_name_tv）;
batteryLevelTV =（TextView中）itemView.findViewById（R.id.battery_level_tv）;
}
}
}
解决方案
修改 getItemCount（）实际返回正确的值：
@覆盖
公众诠释getItemCount（）{
返回data.size（）
}
I'm in a fragment trying to updated my recycler view, after querying Parse for some data. In the done method of the query I call notifyDataSetChagned, but the list is never displayed
package com.garciaericn.t2d.fragments;
public class DevicesCardViewFragment extends Fragment implements View.OnClickListener {
private OnFragmentInteractionListener mListener;
private BatteryHelper mBatteryHelper;
Intent mBatteryStatus;
private RecyclerView mRecyclerView;
private DeviceAdapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private List<Device> mDevices;
public DevicesCardViewFragment() {
// Required empty public constructor
mDevices = new ArrayList<Device>();
}
public static DevicesCardViewFragment newInstance() {
// Bundle parameters is necessary
return new DevicesCardViewFragment();
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get arguments
getDevices();
mBatteryHelper = new BatteryHelper(getActivity());
IntentFilter intentFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
mBatteryStatus = getActivity().registerReceiver(null, intentFilter);
// Update stats of current device.
Toast.makeText(getActivity(), "Battery level: " + mBatteryHelper.getCurrentBatteryLevel() + "%", Toast.LENGTH_LONG).show();
// Update device stats
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_devices_list, container, false);
mListener.showAd();
// Obtain recycler view
mRecyclerView = (RecyclerView) view.findViewById(R.id.devices_recycler_view);
mRecyclerView.setHasFixedSize(true);
mAdapter = new DeviceAdapter(getActivity(), mDevices);
// Set adapter
mRecyclerView.setAdapter(mAdapter);
// Set layout manager
mLayoutManager = new LinearLayoutManager(getActivity());
mRecyclerView.setLayoutManager(mLayoutManager);
return view;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public List<Device> getDevices() {
ParseQuery<Device> query = ParseQuery.getQuery(Device.DEVICES);
// new ParseQuery<Device>(Device.DEVICES);
query.whereEqualTo("deviceUser", ParseUser.getCurrentUser());
query.findInBackground(new FindCallback<Device>() {
@Override
public void done(List<Device> devices, ParseException e) {
if (e == null) {
// Loop through return devices
for (Device device : devices) {
Device currentDevice = new Device();
currentDevice.setDeviceName(device.getDeviceName());
currentDevice.setBatteryLevel(device.getBatteryLevel());
currentDevice.setIsCharging(device.isCharging());
mDevices.add(currentDevice);
}
mAdapter.notifyDataSetChanged();
} else {
// Something went wrong
Toast.makeText(getActivity(), "Error: " + e.toString(), Toast.LENGTH_LONG).show();
}
}
});
return mDevices;
}
@Override
public void onClick(View v) {
// Click events go here
}
public static DevicesCardViewFragment newInstance(List<Device> mDevices) {
DevicesCardViewFragment fragment = new DevicesCardViewFragment();
Bundle args = new Bundle();
return fragment;
}
public interface OnFragmentInteractionListener {
public void showAd();
}
}
My recyclerViewAdapter looks like this...
package com.garciaericn.t2d.data;
public class DeviceAdapter extends RecyclerView.Adapter<DeviceAdapter.MyViewHolder> {
private final LayoutInflater inflater;
List<Device> data = Collections.emptyList();
public DeviceAdapter(Context context, List<Device> data) {
inflater = LayoutInflater.from(context);
this.data = data;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = inflater.inflate(R.layout.card_layout, parent, false);
MyViewHolder holder = new MyViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
Device device = data.get(position);
holder.deviceNameTV.setText(device.getDeviceName());
holder.batteryLevelTV.setText(device.getBatteryLevel());
}
@Override
public int getItemCount() {
return 0;
}
public static class MyViewHolder extends RecyclerView.ViewHolder {
// Temp data set
private String[] mDataset;
TextView deviceNameTV;
TextView batteryLevelTV;
public MyViewHolder(View itemView) {
super(itemView);
deviceNameTV = (TextView) itemView.findViewById(R.id.device_name_tv);
batteryLevelTV = (TextView) itemView.findViewById(R.id.battery_level_tv);
}
}
}
解决方案
Change getItemCount() to actually return the correct value:
@Override
public int getItemCount() {
return data.size()
}
这篇关于分析查询后RecyclerView notifyDataSetChanged不工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
