android - 将从 firebase 检索到的键值添加到 arraylist 不起作用

Question

我正在使用 recyclerview 显示来自 firebase 的数据。我使用数组列表存储它们来自 firebase 的键值，然后使用该数组列表填充回收器 View ，但这里的问题是键值没有添加到列表中，但是当我使用 toast 显示键时重视它的工作正常。我犯了什么错误，我该如何解决？

package com.sabari.inventory;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity implements MyAdapter.ClickListener{

RecyclerView recyclerView;
MyAdapter adapter;
List<Info> infos;
DatabaseReference myRef,dr;
List<String> tit,d;
int position;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    recyclerView = (RecyclerView) findViewById(R.id.myRecView);
    tit = new ArrayList<>();
    d = new ArrayList<>();

    myRef = FirebaseDatabase.getInstance().getReference();
    dr = myRef.child("Machines");
    adapter = new MyAdapter(getApplicationContext(),getData());
    adapter.setClickListener(this);
    recyclerView.setAdapter(adapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));

}

public List<Info> getData(){

    infos = new ArrayList<>();
    dr.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            tit.add(dataSnapshot.getKey());
            adapter.notifyDataSetChanged();
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    for(int i=0;i<tit.size();i++) {
        Info now = new Info();
        now.title = tit.get(i);
        now.desc = "";
        infos.add(now);
    }return infos;
}

@Override
public void itemClicked(View view, int position) {
        MyDialog myDialog = new MyDialog();
        myDialog.show(getSupportFragmentManager(),"");

}
}

信息类

package com.sabari.inventory;



public class Info {

int img;
String title;
String desc;
}

适配器类

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyVH>  {

LayoutInflater layoutInflater;
Context context;
ClickListener clickListener;
List<Info> infoList = Collections.emptyList();
public MyAdapter(Context context,List<Info> infoList) {
    layoutInflater=LayoutInflater.from(context);
    this.infoList = infoList;
    this.context=context;
}

@Override
public MyVH onCreateViewHolder(ViewGroup parent, int viewType) {
    View view=layoutInflater.inflate(R.layout.single_row,parent,false);
    MyVH myVH = new MyVH(view);
    return myVH;
}

@Override
public void onBindViewHolder(MyVH holder, final int position) {
    Info now = infoList.get(position);
    holder.textView1.setText(now.title);
    holder.textView2.setText(now.desc);
}

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

public void setClickListener(ClickListener clickListener)
{
    this.clickListener=clickListener;
}



class MyVH extends RecyclerView.ViewHolder implements View.OnClickListener{

    ImageView imageView;
    TextView textView1,textView2;
    public MyVH(View itemView) {
        super(itemView);
        imageView = (ImageView) itemView.findViewById(R.id.imageView);
        textView1 = (TextView) itemView.findViewById(R.id.textView);
        textView2 = (TextView) itemView.findViewById(R.id.textView2);

        itemView.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        if(clickListener!=null)
        {
            clickListener.itemClicked(view,getPosition());
        }
    }
}

public interface ClickListener{
    public void itemClicked(View view,int position);

}
}

修改 getData() 方法

 public List<Info> getData(){

    infos = new ArrayList<>();

    dr.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Info info= dataSnapshot.getValue(Info.class);
            tit.add(info.getTitle());
            adapter.notifyDataSetChanged();
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    for(int i=0;i<1;i++) {
        Info now = new Info();
        now.title = tit.get(i);
        now.desc = "";
        infos.add(now);
    }return infos;
}

Answer 1

将您的 Info.class 创建为对象:

public class Info {

int img;
String title;
String desc;

public Info() {};

public Info(int img, String title, String desc) {
    this.img = img;
    this.title = title;
    this.desc = desc;
}
public int getImg() { return img; }
public String getTitle() { return title; }
public String getDesc() { return desc; }
}

在你的监听器中

@Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        Info info = dataSnapshot.getValue(Info.class);
        tit.add(info.getTitle());
        adapter.notifyDataSetChanged();
    }