Recycler View 无法在布局中加载数据

Question

当我尝试运行应用程序时，我的回收器视图无法生成输出。无法加载数据，代码没有错误。

下面是适配器class PlayerListAdapter.java

public class PlayerListAdapter extends RecyclerView.Adapter<PlayerListAdapter.FeaturedViewHolder> {

    ArrayList<plaerListHelperClass> featuredLocation;

    public PlayerListAdapter(ArrayList<plaerListHelperClass> featuredLocation) {
        this.featuredLocation = featuredLocation;
    }

    @NonNull
    @Override
    public FeaturedViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.playerlist,parent,false);
        FeaturedViewHolder featuredViewHolder= new FeaturedViewHolder(view);
        return featuredViewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull FeaturedViewHolder holder, int position) {

        plaerListHelperClass plaerListHelperClass = featuredLocation.get(position);
        String namep= plaerListHelperClass.getPlayerName();
        String mailp= plaerListHelperClass.getPlayerEmail();

        holder.name.setText(namep);
        holder.mail.setText(mailp);

    }

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

    public static class FeaturedViewHolder extends RecyclerView.ViewHolder{

        TextView name,mail;

        public FeaturedViewHolder(@NonNull View itemView) {
            super(itemView);

            name=itemView.findViewById(R.id.playerName);
            mail=itemView.findViewById(R.id.pmail);
        }
    }

mainactivity.java 这是我代码

的主要activity

public class MainActivity extends AppCompatActivity {
    RecyclerView featuredRecycler;
    RecyclerView.Adapter adapter;

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

        featuredRecycler=findViewById(R.id.playerListRecyclerView);

        featuredRecycler();
    }

    private void featuredRecycler() {
        featuredRecycler.setHasFixedSize(true);

        ArrayList<plaerListHelperClass> featuredLocation = new ArrayList<>();

        featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
        featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
        featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
        featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));

        adapter=new PlayerListAdapter(featuredLocation);

        featuredRecycler.setAdapter(adapter);

    }

构建此助手 class 以包含要发送到回收器视图布局的元素

plaerListHelperClass.java

public class plaerListHelperClass {
    String playerName;
    String playerEmail;

    public plaerListHelperClass(String playerName, String playerEmail) {
        this.playerName = playerName;
        this.playerEmail = playerEmail;
    }

    public String getPlayerName() {
        return playerName;
    }

    public String getPlayerEmail() {
        return playerEmail;
    }
}

playerlist.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white">
    <TextView
        android:id="@+id/playerName"
        android:layout_height="wrap_content"
        android:textColor="#897668"
        android:layout_weight="1.50"
        android:layout_width="match_parent"
        android:layout_marginTop="10dp"
        android:layout_marginLeft="0dp"/>
    <TextView
        android:id="@+id/pmail"
        android:layout_height="wrap_content"
        android:textColor="#897668"
        android:layout_below="@+id/name"
        android:layout_width="match_parent"
        android:layout_weight="1"
        android:layout_marginTop="10dp"
        android:layout_centerHorizontal="true"/>



</LinearLayout>

activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent"
    tools:context=".MainActivity"
    android:background="@color/white">

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/playerListRecyclerView"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

欢迎来到 Stack Overflow，

你的实现是正确的，但我猜你忘了为 RecyclerView 添加布局管理器。

因此您可以通过将其添加到 xml 或您的 java class 中来实现此目的：

activity_main.xml

    <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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="match_parent"
    tools:context=".MainActivity"
    android:background="@color/white">

<!--    for Linear layout...-->
    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/playerListRecyclerView"
        tools:listitem="@layout/playerlist"
        tools:itemCount="7"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>

或者，

您可以将其添加到您的 java class 作为

 private void featuredRecycler() {
            featuredRecycler.setHasFixedSize(true);
    
            ArrayList<plaerListHelperClass> featuredLocation = new ArrayList<>();
    
            featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
            featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
            featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
            featuredLocation.add(new plaerListHelperClass("Shubham","Shubham@gmail.com"));
    
            adapter=new PlayerListAdapter(featuredLocation);
    
            featuredRecycler.setAdapter(adapter);
            featuredRecycler.setLayoutManager(new LinearLayoutManager(this@MainActivity))

        }

更多参考可以参考https://www.javatpoint.com/android-recyclerview-list-example

Recycler View 无法在布局中加载数据

Recycler View Unable to load data in the layout

java

android

android-recyclerview