recyclerview不显示片段中的sqlite数据

Question

Code

public class UsageSettings2 extends Fragment {
MainData mDatabaseHelper;
RecyclerView mRecyclerView;
UserDataHelper mHelper;
private List<UsageHelper> usage = new ArrayList<>();
private LinearLayoutManager linearLayoutManager;
private UsageAdapter mAdapter;
SQLiteDatabase db;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View rootView =  inflater.inflate(R.layout.settings_usage2, container, false);

    final MainData myDBHlpr = new MainData(getActivity());
    db = myDBHlpr.getWritableDatabase();

    mRecyclerView = (RecyclerView) rootView.findViewById(R.id.usagelist);
        //Add the data first
        linearLayoutManager = new LinearLayoutManager(getActivity());
        //and then create a object and pass the lis
        mAdapter = new UsageAdapter(usage);

    mRecyclerView.setLayoutManager(linearLayoutManager);
    mRecyclerView.setAdapter(mAdapter);
    mAdapter.notifyDataSetChanged();

    Cursor csr = myDBHlpr.getAllQuestions2(getActivity());
    while (csr.moveToNext()) {

        String name = csr.getString(csr.getColumnIndex("Name"));
        int sent = csr.getInt(csr.getColumnIndex("MessagesSent"));
        int recieved = csr.getInt(csr.getColumnIndex("MessagesRecieved"));
        int total = csr.getInt(csr.getColumnIndex("Messages"));
        String time = csr.getString(csr.getColumnIndex("TimeSpent"));

        new UsageHelper(name,sent,recieved,total,time);


        int profile_counts = myDBHlpr.getProfilesCount2();
        Log.d("FFF", String.valueOf(profile_counts));


    }



        return rootView;
    }
}

Adapter

public class UsageAdapter extends RecyclerView.Adapter<UsageAdapter.UsageViewHolder>{

private List<UsageHelper> mUsageHelper;

public UsageAdapter(List<UsageHelper> UsageAdapter) {
    this.mUsageHelper = UsageAdapter;
}

public class UsageViewHolder extends RecyclerView.ViewHolder{
    public TextView mName;
    public TextView mSent;
    public TextView mRecieved;
    public TextView mTotal;
    public TextView mTime;

    public UsageViewHolder(View view) {
        super(view);
        mName = (TextView)view.findViewById(R.id.name);
        mSent = (TextView)view.findViewById(R.id.sent);
        mRecieved = (TextView)view.findViewById(R.id.recieved);
        mTotal = (TextView)view.findViewById(R.id.total);
        mTime = (TextView)view.findViewById(R.id.time);
    }
}

@Override
public UsageAdapter.UsageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View V = LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_activity_usage,parent,false);
    return new UsageAdapter.UsageViewHolder(V);
}

@Override
public void onBindViewHolder(final UsageViewHolder holder, int position) {
    final UsageHelper usageHelper = mUsageHelper.get(position);

    holder.mName.setText(usageHelper.getName());
    holder.mSent.setText(usageHelper.getSent());
    holder.mRecieved.setText(usageHelper.getRecieved());
    holder.mTotal.setText(usageHelper.getTotal());
    holder.mTime.setText(usageHelper.getTime());

}


@Override
public  int getItemCount() {
    return mUsageHelper.size();
}

Modal

public class UsageHelper {
private String Name;
private int Sent;
private int Recieved;
private int Total;
private String Time;

public UsageHelper() {
}

public UsageHelper(String Name, int Sent ,int Recieved, int Total, String Time) {

    this.Name = Name;
    this.Sent = Sent;
    this.Recieved = Recieved;
    this.Total = Total;
    this.Time = Time;
}

public String getName() {
    return Name;
}

public void setName(String name) {
    this.Name = name;
}

public int getSent() {
    return Sent;
}

public void setSent(int sent) {
    this.Sent = sent;
}

public int getRecieved() {
    return Recieved;
}

public void setRecieved(int recieved) {
    this.Recieved = recieved;
}

public String getTime() {
    return Time;
}

public void setTime(String time) {
    this.Time = time;
}

public int getTotal() {
    return Total;
}

public void setTotal(int total) {
    this.Total = total;
}

}

The problem is that its not showing anything... the fragment is blank when i open it although the data is present... Any idea why its now showing any data? Im not getting any error just that the data isnt showing..........................................................................

Got an error after making changes according to answers

Custom

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/usage"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/black">

<RelativeLayout
    android:weightSum="1"
    android:id="@+id/linear"
    android:padding="1dp"
    android:background="@color/white"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:textSize="15dp"
        android:layout_toLeftOf="@+id/mid"
        android:text="Name"
        android:layout_alignParentStart="true"
        android:id="@+id/name"
        android:paddingVertical="10dp"
        android:background="@color/black"
        android:gravity="center_horizontal"
        android:textColor="@color/white"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />



    <TextView
        android:id="@+id/sent"
        android:layout_toRightOf="@id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@color/black"
        android:gravity="center_horizontal"
        android:paddingVertical="10dp"
        android:text="Sent"
        android:textColor="@color/white"
        android:textSize="15dp" />

    <TextView
        android:id="@+id/recieved"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/sent"
        android:background="@color/black"
        android:gravity="center_horizontal"
        android:paddingVertical="10dp"
        android:text="Recieved"
        android:textColor="@color/white"
        android:textSize="15dp" />

    <TextView
        android:id="@+id/total"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/recieved"
        android:background="@color/black"
        android:gravity="center_horizontal"
        android:paddingVertical="10dp"
        android:text="Total"
        android:textColor="@color/white"
        android:textSize="15dp" />

    <TextView
        android:id="@+id/time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/recieved"
        android:background="@color/black"
        android:gravity="center_horizontal"
        android:paddingVertical="10dp"
        android:text="Time \nSpent"
        android:textColor="@color/white"
        android:textSize="15dp" />


</RelativeLayout>

Answer 1

In the while loop of onCreateView() , add each row from the db to the list:

usage.add(new UsageHelper(name,sent,recieved,total,time));

instead of just:

new UsageHelper(name,sent,recieved,total,time)

which does nothing.
And after the loop finishes:

mAdapter.notifyDataSetChanged();

so the RecyclerView loads all the added rows to the list.
Edit
Replace

holder.mSent.setText(usageHelper.getSent());

with

holder.mSent.setText("" + usageHelper.getSent());

because usageHelper.getSent() is int and it is treated as a resource id.

Answer 2

The usage list is always empty because you are not adding the new "UsageHelper" you are creating from your Cursor into the list.

What you need to do is the following:

Cursor csr = myDBHlpr.getAllQuestions2(getActivity());
while (csr.moveToNext()) {

    ...

    UsageHelper newListItem = new UsageHelper(name,sent,recieved,total,time);
    usage.add(newListItem);

    ...

}
mAdapter.notifyDataSetChanged();

When you finish adding elements to the list, you want to notify your adapter that the list has new items, so you have to call to mAdapter.notifyDataSetChanged(); and the new elements will be displayed

Answer 3

add mAdapter.notifyDataSetChanged(); in while condition or after adding your data in model class.