Android Java页面OkHttp获取JSON成功但ListView不显示数据

列表空白核心是网络请求时序逻辑写错了：

• 你在AsyncTask的doInBackground里调用OkHttp的enqueue发异步请求，这个方法是非阻塞的，请求会丢给OkHttp自己的线程池执行，doInBackground会立刻执行return null，马上触发onPostExecute。
• 这时候OkHttp的响应还没回来，resultList是空的，你把空集合传给SimpleAdapter绑定ListView，当然显示空白。等后续回调把数据塞进resultList的时候，Adapter早就初始化完成了，感知不到数据变化，不会刷新界面。

另外还有几个隐患：

• 子线程直接修改resultList没有加同步，存在并发修改风险
• 重复导入java.util.ArrayList，还有Gson、SearchView、ArrayAdapter等一堆没用到的冗余导入，虽然不影响运行但没必要留
• OkHttp回调本身在子线程，就算数据加载完你直接更新UI也会崩溃，必须切主线程

两种改法二选一，不要混着写多套异步逻辑：

方案1：OkHttp改同步调用，适配现有AsyncTask逻辑 #

去掉enqueue异步回调，直接用OkHttp同步方法execute()，在doInBackground里直接完成响应读取、JSON解析，等所有数据处理完再返回，这样onPostExecute执行的时候resultList里已经有完整数据了。

doInBackground修改后核心代码：

@Override
protected Void doInBackground(Void... arg0) {
    OkHttpClient client = new OkHttpClient();
    Request request = new Request.Builder()
            .url("https://heisenbug-premier-league-live-scores-v1.p.rapidapi.com/api/premierleague/team?name=Liverpool")
            .get()
            .addHeader("X-RapidAPI-Key", "替换成你自己的有效Key")
            .addHeader("X-RapidAPI-Host", "heisenbug-premier-league-live-scores-v1.p.rapidapi.com")
            .build();
    try {
        Response response = client.newCall(request).execute();
        if (!response.isSuccessful()) return null;
        String jsonStr = response.body().string();
        Log.e(TAG, "Response from url: " + jsonStr);
        if (jsonStr == null) return null;
        JSONObject jsonObj = new JSONObject(jsonStr);
        JSONArray records = jsonObj.getJSONArray("records");
        for (int i = 0; i < records.length(); i++) {
            JSONObject c = records.getJSONObject(i);
            HashMap<String, String> result = new HashMap<>();
            result.put("league",c.getString("league"));
            result.put("season",c.getString("season"));
            result.put("name",c.getString("name"));
            result.put("officialName",c.getString("officialName"));
            result.put("address",c.getString("address"));
            result.put("telephone",c.getString("telephone"));
            result.put("fax",c.getString("fax"));
            result.put("website",c.getString("website"));
            result.put("founded",c.getString("founded"));
            result.put("teamSize",c.getString("teamSize"));
            result.put("averageAge",c.getString("averageAge"));
            result.put("foreigners",c.getString("foreigners"));
            result.put("nationaTeamPlayers",c.getString("nationaTeamPlayers"));
            result.put("teamValue",c.getString("teamValue"));
            result.put("venue",c.getString("venue"));
            result.put("venueCapacity",c.getString("venueCapacity"));
            resultList.add(result);
        }
    } catch (IOException | JSONException e) {
        Log.e(TAG, "加载失败: " + e.getMessage());
        runOnUiThread(() -> Toast.makeText(getApplicationContext(),
                "数据加载失败: " + e.getMessage(), Toast.LENGTH_LONG).show());
    }
    return null;
}

方案2：删掉多余的AsyncTask，直接用OkHttp异步回调处理 #

AsyncTask本身在高版本Android已经被废弃，完全没必要多包一层。直接在onCreate里发起OkHttp异步请求，等回调里解析完所有数据，再切到主线程给ListView绑定Adapter即可。

核心逻辑示例：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_team_info);
    resultList = new ArrayList<>();
    lv = findViewById(R.id.list);
    Toast.makeText(this,"Json Data is downloading",Toast.LENGTH_LONG).show();

    OkHttpClient client = new OkHttpClient();
    Request request = new Request.Builder()
            .url("https://heisenbug-premier-league-live-scores-v1.p.rapidapi.com/api/premierleague/team?name=Liverpool")
            .get()
            .addHeader("X-RapidAPI-Key", "替换成你自己的有效Key")
            .addHeader("X-RapidAPI-Host", "heisenbug-premier-league-live-scores-v1.p.rapidapi.com")
            .build();
    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(@NonNull Call call, @NonNull IOException e) {
            runOnUiThread(() -> Toast.makeText(TeamInfo.this, "网络请求失败", Toast.LENGTH_LONG).show());
        }

        @Override
        public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
            String jsonStr = response.body().string();
            Log.e(TAG, "Response from url: " + jsonStr);
            if (jsonStr != null) {
                try {
                    JSONObject jsonObj = new JSONObject(jsonStr);
                    JSONArray records = jsonObj.getJSONArray("records");
                    for (int i = 0; i < records.length(); i++) {
                        JSONObject c = records.getJSONObject(i);
                        HashMap<String, String> result = new HashMap<>();
                        result.put("league",c.getString("league"));
                        result.put("season",c.getString("season"));
                        result.put("name",c.getString("name"));
                        result.put("officialName",c.getString("officialName"));
                        result.put("address",c.getString("address"));
                        result.put("telephone",c.getString("telephone"));
                        result.put("fax",c.getString("fax"));
                        result.put("website",c.getString("website"));
                        result.put("founded",c.getString("founded"));
                        result.put("teamSize",c.getString("teamSize"));
                        result.put("averageAge",c.getString("averageAge"));
                        result.put("foreigners",c.getString("foreigners"));
                        result.put("nationaTeamPlayers",c.getString("nationaTeamPlayers"));
                        result.put("teamValue",c.getString("teamValue"));
                        result.put("venue",c.getString("venue"));
                        result.put("venueCapacity",c.getString("venueCapacity"));
                        resultList.add(result);
                    }
                    // 切主线程绑定Adapter
                    runOnUiThread(() -> {
                        ListAdapter adapter = new SimpleAdapter(TeamInfo.this, resultList,
                                R.layout.list_item_team, new String[]{ "league","season","name","officialName","address","telephone","fax","website","founded","teamSize","averageAge","foreigners","nationaTeamPlayers","teamValue","venue","venueCapacity"},
                                new int[]{R.id.league, R.id.season,R.id.name,R.id.officialName,R.id.address,R.id.telephone,R.id.fax,R.id.website,R.id.founded,R.id.teamSize,R.id.averageAge,R.id.foreigners,R.id.nationaTeamPlayers,R.id.teamValue,R.id.venue,R.id.venueCapacity});
                        lv.setAdapter(adapter);
                    });
                } catch (final JSONException e) {
                    Log.e(TAG, "Json parsing error: " + e.getMessage());
                    runOnUiThread(() -> Toast.makeText(getApplicationContext(),
                            "Json parsing error: " + e.getMessage(), Toast.LENGTH_LONG).show());
                }
            }else {
                Log.e(TAG, "Couldn't get json from server.");
                runOnUiThread(() -> Toast.makeText(getApplicationContext(),
                        "Couldn't get json from server. Check LogCat for possible errors!",
                        Toast.LENGTH_LONG).show());
            }
        }
    });
}

• 确认AndroidManifest.xml里已经加了网络权限：<uses-permission android:name="android.permission.INTERNET" />，否则高版本系统会直接拦截网络请求
• 所有UI相关操作（弹Toast、绑定Adapter、更新View）必须在主线程执行，OkHttp的回调默认在子线程，必须用runOnUiThread切换
• 删掉没用的冗余导入，避免不必要的编译警告

内容的提问来源于stack exchange，提问作者Brie