需要帮助来检索所有数据到listview

Question

我正在尝试制作一个可以从数据库读取数据的android应用程序。但是当我尝试在列表视图中显示一些行时，仅显示我编写的代码的底部行。

这是我的MainActivity代码

public class MainActivity extends AppCompatActivity {

    ListView listView;

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

        listView = findViewById(R.id.listView);
        getJSON("http://192.168.137.234/librenms/getdata.php");

    }

    private void getJSON(final String urlWebService) {
        class GetJSON extends AsyncTask<Void, Void, String> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
            }

            @Override
            protected void onPostExecute(String s) {
                super.onPostExecute(s);
                try {
                    loadIntoListView(s);
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }

            @Override
            protected String doInBackground(Void... voids) {
                try {
                    URL url = new URL(urlWebService);
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();
                    StringBuilder sb = new StringBuilder();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
                    String json;
                    while ((json = bufferedReader.readLine()) !=null) {
                        sb.append(json).append("\n");
                    }
                    return sb.toString().trim();
                } catch (Exception e) {
                    return null;
                }
            }
        }
        GetJSON getJSON = new GetJSON();
        getJSON.execute();
    }

    private void loadIntoListView(String json) throws JSONException {
        JSONArray jsonArray = new JSONArray(json);
        String[] alerts = new String[jsonArray.length()];

这是在列表视图上显示属性的部分

        for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject object = jsonArray.getJSONObject(i);
            alerts[i] = object.getString("Rule ID");
            alerts[i] = object.getString("Device ID");
            alerts[i] = object.getString("Time logged");
        }
        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, alerts);
        listView.setAdapter(arrayAdapter);
    }
}