android - 回收 View 仅显示 1 个元素

Question

我正在使用 Firebase 在我的应用程序上实现一些逻辑。

我需要使用回收 View 和自定义适配器为我的用户设置一些信息，问题是每次我执行 prepareData() 时，只显示 1 个元素而不是我的所有数组，我认为它可以有一些东西与我的布局有关，因为在适配器上我收到了所有信息。

所以在我的主要 Activity 中我有这个:

package com.esmad.pdm.friendlymanager;

import android.content.Intent;
import android.icu.text.MessagePattern;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

import com.esmad.pdm.friendlymanager.model.Event;
import com.esmad.pdm.friendlymanager.model.EventViewModel;
import com.esmad.pdm.friendlymanager.model.Participant;
import com.esmad.pdm.friendlymanager.other.EventGameAdapter;
import com.esmad.pdm.friendlymanager.other.Participants;
import com.google.firebase.auth.FirebaseAuth;
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 com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;

public class MatchInvitation extends AppCompatActivity {

    FirebaseDatabase database;
    DatabaseReference myRef;
    DatabaseReference user;
    private FirebaseAuth auth;
    String id;
    String username;
    RecyclerView ps;
    Participants participantAdapter;
    TextView title1;
    ArrayList<Participant> participants;
    boolean exists;
    String matchId;


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

        participants = new ArrayList<>();
        title1 = (TextView)findViewById(R.id.textView3);
        database = FirebaseDatabase.getInstance();
        myRef = database.getReference("Matches");
        user = database.getReference("Users");
        auth = FirebaseAuth.getInstance();
        id = auth.getCurrentUser().getUid();

        Intent i = getIntent();
        Bundle extras = i.getExtras();
        if (extras != null) {
            if (extras.containsKey("matchId")) {
                matchId = getIntent().getStringExtra("matchId");
            }
        }



        ps = (RecyclerView)findViewById(R.id.participants);

        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);

        ps = (RecyclerView)findViewById(R.id.participants);
        ps.setHasFixedSize(true);
        ps.setLayoutManager(linearLayoutManager);

        participantAdapter = new Participants(getApplicationContext(), participants);
        ps.setAdapter(participantAdapter);

        loadParticipants();
        //loadDataTeamA();
        //loadDataTeamB();
    }

    public void remove(View view){
        myRef.child(matchId).child("Participants")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                            if(snapshot.getKey().equals(id)){
                                for(Participant p: participants){
                                    if(p.getUserId().equals(id)){
                                        participants.remove(p);
                                    }
                                }
                                snapshot.getRef().setValue(null);
                            }
                        }
                        participantAdapter.notifyDataSetChanged();
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {
                        Log.d("failed", "here");
                    }

                });
    }

    public void add(View view){
        getUser();
    }


    public void loadParticipants(){
        myRef.child(matchId).child("Participants")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                            Participant x = new Participant(snapshot.getKey(),snapshot.getValue().toString());
                            participants.add(x);
                        }
                        participantAdapter.notifyDataSetChanged();
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {
                        Log.d("failed", "here");
                    }

                });
    }

    public void participantExist(final String id){
        myRef.child("Participants").child("matchId")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                            if(snapshot.getKey().equals(id)){
                                exists = true;
                            }
                        }
                        participantAdapter.notifyDataSetChanged();
                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {
                        Log.d("failed", "here");
                    }

                });
    }


public void getUser() {
    user.child(id).addListenerForSingleValueEvent(new ValueEventListener() {

        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.getKey().equals(id)) {
                username = dataSnapshot.child("username").getValue().toString();
                myRef.child(matchId).child("Participants").child(id).setValue(username);
                Participant x = new Participant(id,username);
                participants.add(x);
                Log.d("arrqwe",String.valueOf(participants.size()));
            }
            if(participants.size() > 0){
                title1.setVisibility(View.VISIBLE);
            }
            participantAdapter.notifyDataSetChanged();
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            Log.d("failed", "here");
        }

    });

}
}

然后在我的 customAdapter 上我有这个:

public class Participants extends RecyclerView.Adapter<Participants.ViewHolder> {


    private ArrayList<Participant> participants;
    private Context context;
    private View cv;

    public Participants(Context context, ArrayList<Participant> participants) {
        this.participants = participants;
        this.context = context;
    }

    @Override
    public Participants.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.username_list, viewGroup, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final Participants.ViewHolder viewHolder, final int i) {
        Log.d("participante",participants.get(i).getUsername());
        viewHolder.name.setText(participants.get(i).getUsername());

    }

    @Override
    public int getItemCount() {
        if (participants != null) {
            return participants.size();
        } else {
            return 0;
        }
    }

    public class ViewHolder extends RecyclerView.ViewHolder{
        private TextView name;
        public ViewHolder(View view) {
            super(view);
            cv = view;
            name = (TextView)view.findViewById(R.id.username);
        }
    }

}

我的单品行

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/username"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

最后是我的 Activity 布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="com.esmad.pdm.friendlymanager.MatchInvitation">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/teamA"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintRight_toLeftOf="@+id/teamB"
        tools:layout_constraintTop_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintBottom_creator="1"
        android:layout_marginStart="7dp"
        app:layout_constraintBottom_toBottomOf="@+id/teamB"
        android:layout_marginEnd="13dp"
        tools:layout_constraintLeft_creator="1"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="@+id/teamB">

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

    <android.support.v7.widget.RecyclerView
        android:id="@+id/teamB"
        android:layout_width="174dp"
        android:layout_height="0dp"
        tools:layout_constraintTop_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintBottom_creator="1"
        app:layout_constraintBottom_toBottomOf="parent"
        android:layout_marginEnd="16dp"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_marginTop="11dp"
        app:layout_constraintTop_toBottomOf="@+id/textView4"
        android:layout_marginBottom="15dp">

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

    <android.support.v7.widget.RecyclerView
        android:id="@+id/participants"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="34dp"
        android:layout_marginEnd="17dp"
        android:layout_marginStart="17dp"
        android:layout_marginTop="34dp"
        app:layout_constraintBottom_toBottomOf="@+id/textView5"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button6"
        tools:layout_constraintBottom_creator="1"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintTop_creator="1" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="participants"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1"
        android:visibility="invisible"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintTop_creator="1"
        android:layout_marginTop="6dp"
        app:layout_constraintTop_toBottomOf="@+id/button5"
        app:layout_constraintLeft_toLeftOf="@+id/button5" />

    <TextView
        android:id="@+id/textView4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="64dp"
        android:text="TeamB"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1"
        android:visibility="invisible"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintTop_creator="1"
        tools:layout_constraintRight_creator="1"
        android:layout_marginEnd="65dp"
        app:layout_constraintRight_toRightOf="@+id/participants"
        android:layout_marginTop="17dp"
        app:layout_constraintTop_toBottomOf="@+id/participants"
        app:layout_constraintLeft_toLeftOf="@+id/teamB" />

    <TextView
        android:id="@+id/textView5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="61dp"
        android:layout_marginStart="58dp"
        android:text="TeamA"
        android:textAppearance="@style/TextAppearance.AppCompat.Body1"
        android:visibility="invisible"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintTop_creator="1"
        app:layout_constraintRight_toRightOf="@+id/teamA"
        android:layout_marginTop="288dp"
        app:layout_constraintLeft_toLeftOf="@+id/participants"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintHorizontal_bias="0.487" />

    <ImageButton
        android:id="@+id/button5"
        android:layout_width="44dp"
        android:layout_height="0dp"
        android:layout_marginStart="16dp"
        android:onClick="add"
        android:src="@drawable/ic_check_black_24dp"
        android:tint="@color/emerald"
        tools:layout_constraintBottom_creator="1"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintTop_creator="1"
        app:layout_constraintRight_toLeftOf="@+id/button6"
        tools:layout_constraintRight_creator="1"
        app:layout_constraintBottom_toBottomOf="@+id/button6"
        android:layout_marginEnd="15dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="@+id/button6" />

    <ImageButton
        android:id="@+id/button6"
        style="@android:style/Widget.DeviceDefault.ImageButton"
        android:layout_width="44dp"
        android:layout_height="0dp"
        android:layout_marginEnd="75dp"
        android:layout_marginStart="75dp"
        android:onClick="remove"
        android:src="@drawable/ic_clear_black_24dp"
        android:tint="@color/red"
        tools:layout_constraintBottom_creator="1"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintTop_creator="1"
        app:layout_constraintRight_toLeftOf="@+id/teamB"
        app:layout_constraintBottom_toBottomOf="@+id/button7"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="@+id/button7" />

    <Button
        android:id="@+id/button7"
        android:layout_width="0dp"
        android:layout_height="48dp"
        android:layout_marginEnd="137dp"
        android:layout_marginStart="137dp"
        android:layout_marginTop="32dp"
        android:text="best teams"
        android:visibility="invisible"
        app:layout_constraintTop_toTopOf="parent"
        tools:layout_constraintLeft_creator="1"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintTop_creator="1"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent" />

    <Button
        android:id="@+id/button8"
        android:layout_width="88dp"
        android:layout_height="48dp"
        android:text="random"
        android:visibility="invisible"
        app:layout_constraintBaseline_toBaselineOf="@+id/button7"
        tools:layout_constraintBaseline_creator="1"
        tools:layout_constraintLeft_creator="1"
        android:layout_marginStart="11dp"
        app:layout_constraintLeft_toRightOf="@+id/button7" />
</android.support.constraint.ConstraintLayout>

Answer 1

在您的单个项目行中，将 LinearLayout android:layout_height 设置为 wrap_content。 android:layout_height="match_parent" 导致每个项目占据整个屏幕。