Android 从Firebase数据库检索数据并显示在RecyclerView上

当我运行应用程序时，它崩溃了，但是在我的代码中我没有看到任何错误。我正在尝试将firebase上的数据检索到

recyclerview

。我正在制作一个帖子评论应用程序。请帮我看看我的代码有什么问题

Java代码

public class DialogComments extends AppCompatActivity implements View.OnClickListener {

    private FirebaseAuth mAuithComment;
    private ProgressDialog mProgressDialog;
    private EditText etComment;
    private DatabaseReference dbRef;
    private FirebaseDatabase mDatabaseComment;
    private RecyclerView recyclerView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dialog_comments);


        recyclerView = (RecyclerView) findViewById(R.id.comment_recyclerview);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        mDatabaseComment = FirebaseDatabase.getInstance();
        dbRef = mDatabaseComment.getReference("UserComments");


    }

    @Override
    protected void onStart(){
        super.onStart();

        FirebaseRecyclerAdapter<CommentModels, CommentViewHolder> firebaseRecyclerAdapter =
                new FirebaseRecyclerAdapter<CommentModels, CommentViewHolder>
                        (
                                CommentModels.class,
                                R.layout.row_comment,
                                CommentViewHolder.class,
                                dbRef
                        )
                {
                    @Override
                    protected void populateViewHolder(CommentViewHolder viewHolder, CommentModels model, int position) {
                        viewHolder.setusername(model.getusername());
                        viewHolder.setcomment(model.getcomment());
                    }
                };

        recyclerView.setAdapter(firebaseRecyclerAdapter);
    }

    public static class CommentViewHolder extends RecyclerView.ViewHolder{
        TextView usernameTextView;
        TextView commentTextView;
        View mView;

        public CommentViewHolder(View itemView){
            super(itemView);
            mView = itemView;
            usernameTextView = (TextView) mView.findViewById(R.id.tv_username);
            commentTextView = (TextView) mView.findViewById(R.id.tv_comment);
        }
        public void setusername(String username){
            usernameTextView.setText(username);

        }
        public void setcomment(String comment){
            commentTextView.setText(comment);
        }
    }


    public void init(){
        etComment = (EditText) findViewById(R.id.et_comment);
        findViewById(R.id.iv_send).setOnClickListener(this);
    }

    public void sendcomment(){

    }

    @Override
    public void onClick(View view) {

        switch (view.getId()) {
            case R.id.iv_send:
                sendcomment();
        }
    }
}

活动对话框注释.xml

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="16dp"
    android:orientation="horizontal">

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_weight="1"
        android:orientation="vertical">

        <TextView
            android:id="@+id/tv_username"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Username"
            android:textColor="@android:color/black"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/tv_comment"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="4dp"
            android:text="dfsd; lfjsd;fk js;dkfj a;sdfj ;sadfj ;sadlkfj ;asdlkfj a;ldskfj ;alkdjfs ;alksdjf ;alkjdsf"
            android:textColor="@android:color/black" />

    </LinearLayout>

   <!-- <TextView
        android:id="@+id/tv_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginRight="16dp"
        android:text="10h30" /
</LinearLayout>
</android.support.v7.widget.CardView>

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="450dp"
    tools:context="com.feu.teamanonymous.ayokotseph_final.Activities.DialogComments"
    android:orientation="vertical">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/comment_recyclerview"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1" >

        </android.support.v7.widget.RecyclerView>

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="8dp">

            <EditText
                android:id="@+id/et_comment"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:hint="Type comment..." />

            <ImageView
                android:id="@+id/iv_send"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="bottom"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="8dp"
                android:src="@drawable/ic_send_black_24dp" />
        </LinearLayout>
    </android.support.v7.widget.CardView>

</LinearLayout>

您是否收到任何错误消息或异常？或者你知道错误发生在哪一行吗？是的，我有一个致命的异常。致命异常：主进程：com.feu.teamanonymous.ayokotseph_final，PID:32744 com.google.firebase.database.DatabaseException:Class com.feu.teamanonymous.ayokotseph_final.Variables.CommentModels缺少一个没有参数的构造函数问题已解决：刚刚在名为public的CommentModels类上添加了一个空白方法CommentModels（）{}

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="450dp"
    tools:context="com.feu.teamanonymous.ayokotseph_final.Activities.DialogComments"
    android:orientation="vertical">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/comment_recyclerview"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1" >

        </android.support.v7.widget.RecyclerView>

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="8dp">

            <EditText
                android:id="@+id/et_comment"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:hint="Type comment..." />

            <ImageView
                android:id="@+id/iv_send"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="bottom"
                android:layout_marginBottom="4dp"
                android:layout_marginLeft="8dp"
                android:src="@drawable/ic_send_black_24dp" />
        </LinearLayout>
    </android.support.v7.widget.CardView>

</LinearLayout>