我无法通过 MySQL、PHP、Volley 按点的降序获取 Android Studio 上的玩家列表

Posted 2023-04-18

【中文标题】我无法通过 MySQL、PHP、Volley 按点的降序获取 Android Studio 上的玩家列表

【英文标题】：I cannot get a list of players on Android Studio via MySQL, PHP, Volley in descending order of points

【发布时间】：2021-05-29 16:42:09

【问题描述】：

我正在尝试使用 RecyclerView 在 android Studio 上显示按分数、照片数量和最高分排名的玩家列表。发生的情况是，我得到一个包含相同用户名、分数、照片和高分的列表，其大小与用户名总数相同

我希望我的 Android 屏幕显示类似的内容... mysql table (via XAMPP)

这是我的 php 代码 - 对我来说似乎很好，因为我已经通过编写 localhost 名称对其进行了测试

<?php

require_once 'connect.php';

$stmt = $conn->prepare("SELECT username, points, photos, highscore FROM users ORDER BY points DESC, photos ASC, highscore DESC;");

$stmt->execute();

$stmt->bind_result($username, $points, $photos, $highscore);

$players = array();

while($stmt->fetch())
    
    $temp = array();
    
    $temp['username'] = $username;
    $temp['points'] = $points;
    $temp['photos'] = $photos;
    $temp['highscore'] = $highscore;
        
    array_push($players, $temp);
    


$stmt->close();

echo json_encode($players);

?>

PHP test via localhost address

如果要在 Android 上显示它，I get the following output...

这是我的 Android 代码：

rankings.java

public class rankings extends AppCompatActivity 

private RecyclerView recyclerView;
private RecyclerView.LayoutManager manager;
private RecyclerView.Adapter mAdapter;
private List<player_object> players;

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

    recyclerView = findViewById(R.id.listView);
    manager = new GridLayoutManager(rankings.this, 1);
    recyclerView.setLayoutManager(manager);
    players = new ArrayList<>();

    getPlayers();


private void getPlayers()
    StringRequest stringRequest = new StringRequest(Request.Method.GET, URLs.URL_RANKING,
            new Response.Listener<String>()
                @Override
                public void onResponse(String response) 
                    try
                        JSONArray array = new JSONArray(response);
                        for (int i = 0 ; i<array.length() ; i++)
                            JSONObject object = array.getJSONObject(i);

                            String player = object.getString("username");
                            int points = object.getInt("points");
                            int photos = object.getInt("photos");
                            int highscore = object.getInt("highscore");

                            player_object gamer = new player_object(player, points, photos, highscore);
                            players.add(gamer);
                        
                     catch(Exception e)
                        e.printStackTrace();
                    

                    mAdapter = new RecyclerAdapter(rankings.this, players);
                    recyclerView.setAdapter(mAdapter);

                
            , new Response.ErrorListener()
        @Override
        public void onErrorResponse(VolleyError error)

            Toast.makeText(rankings.this, "internet gone", Toast.LENGTH_SHORT).show();
        
    );

    Volley.newRequestQueue(rankings.this).add(stringRequest);

RecyclerAdapter.java

public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.MyViewHolder> 

private Context context;
private List<player_object> players;

public RecyclerAdapter (Context context, List<player_object> players)
    this.context = context;
    this.players = players;


@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) 

    View view = LayoutInflater.from(context).inflate(R.layout.activity_rankings_row,parent,false);
    return new MyViewHolder(view);


@Override
public void onBindViewHolder(MyViewHolder holder, int position) 

    player_object player = players.get(position);

    holder.rank.setText(Integer.toString(position+1));
    holder.gamer.setText(player.getPlayer());
    holder.points.setText(Integer.toString(player.getPoints()));
    holder.photos.setText(Integer.toString(player.getPhotos()));
    holder.highscore.setText(Integer.toString(player.getHighscore()));


@Override
public int getItemCount() 
    return players.size();


/*public*/ class MyViewHolder extends RecyclerView.ViewHolder 
    /*private*/ TextView rank;
    /*private*/ TextView gamer;
    /*private*/ TextView points;
    /*private*/ TextView photos;
    /*private*/ TextView highscore;
    /*private*/ LinearLayout container;

    public MyViewHolder (View view)
        super(view);

        rank = view.findViewById(R.id.textView_rank);
        gamer = view.findViewById(R.id.textView_player);
        points = view.findViewById(R.id.textView_points);
        photos = view.findViewById(R.id.textView_photos);
        highscore = view.findViewById(R.id.textView_highscore);
        container = view.findViewById(R.id.player_container);
    

player_object.java

public class player_object 

private static String gamer;
private static int points;
private static int photos;
private static int highscore;

public player_object(String gamer, int points, int photos, int highscore) 
    this.gamer = gamer;
    this.points = points;
    this.photos = photos;
    this.highscore = highscore;


public String getPlayer()
    return gamer;


public int getPoints()
    return points;


public int getPhotos()
    return photos;


public int getHighscore()
    return highscore;


public void setPlayer(String gamer)
    this.gamer = gamer;


public void setPoints(int points)
    this.points = points;


public void setPhotos(int photos)
    this.photos = photos;


public void setHighscore(int highscore)
    this.highscore = highscore;

【参考方案1】：

在player_object 中，从每个类变量中删除static。它们将采用最后设置的值，因为它们与您创建的对象无关。