JSON 解析为 listview/arrayadapter

Question

我正在制作一个将 JSON 数据解析为列表视图的应用程序。这对我不起作用；它没有给我任何数据。

这是我的代码：

public class MainActivity extends AppCompatActivity {

ListView listview;
ArrayAdapter<String> adapter;
String[] data;

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

    listview = (ListView)findViewById(R.id.listview);

    StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().permitNetwork().build());

    MPWebservice();

    listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Intent intent = new Intent(MainActivity.this, bestelling.class);
            intent.putExtra("naam", listview.getItemAtPosition(position).toString());
            startActivity(intent);
        }
    });

}


private void MPWebservice() {
    String Webadres = null;
    String dbResult = "empty";
    dbConnect database = new dbConnect(this);

    try {
        String query = "SELECT * FROM orders";
        Webadres = "?query=" + URLEncoder.encode(query, "UTF-8");
        String con = "https://amje.000webhostapp.com/mariosPizzaJSON.php" + Webadres;
        dbResult = database.execute(con).get();
    } catch (Exception e) {
        e.printStackTrace();
    }

    try {
        JSONArray arr = new JSONArray(dbResult);
        JSONObject jo = null;
        data = new String[arr.length()];

        for (int i = 0; i < 1; i++) {
            jo = arr.getJSONObject(i);
            data[i] = jo.getString("name");
        }
        adapter = new ArrayAdapter<String>(this, R.layout.layout_list, R.id.list_item, data);
        listview.setAdapter(adapter);
    } catch (Exception e) {
        e.printStackTrace();
    }
}
  }

这是 logcat 中的错误：

of type org.json.JSONObject cannot be converted to JSONArray

这是网络服务中的json：

{
   "orders":[
      {
         "naam":"J. Peeters",
         "adres":"Kettingstraat 12",
         "postcode":"5611 RD",
         "bestelling":[
            {
               "Pizza":"Napolitane"
            },
            {
               "Pizza":"Margarita"
            }
         ]
      },
      {
         "naam":"H. Wissink",
         "adres":"Frederik van Eedenplein 5",
         "postcode":"5611 KT",
         "bestelling":[
            {
               "Pizza":"4-Stagione"
            },
            {
               "Pizza":"Siciliane"
            },
            {
               "Pizza":"4-Stagione"
            }
         ]
      },
      {
         "naam":"M. Huisman",
         "adres":"Hertogstraat 17",
         "postcode":"5611 PB",
         "bestelling":[
            {
               "Pizza":"4-Stagione"
            },
            {
               "Pizza":"Napolitane"
            },
            {
               "Pizza":"4-Stagione"
            },
            {
               "Pizza":"Siciliane"
            },
            {
               "Pizza":"Salami"
            }
         ]
      },
      {
         "naam":"H. Moors",
         "adres":"Mauritsstraat 9",
         "postcode":"5611 GV",
         "bestelling":[
            {
               "Pizza":"Calzone"
            }
         ]
      },
      {
         "naam":"H. Jansen",
         "adres":"Stationsplein 23",
         "postcode":"5611 AC",
         "bestelling":[
            {
               "Pizza":"4-Stagione"
            },
            {
               "Pizza":"4-Stagione"
            }
         ]
      },
      {
         "naam":"G.M. Verkuijlen-vd Ven",
         "adres":"Tramstraat 54",
         "postcode":"5611 CR",
         "bestelling":[
            {
               "Pizza":"Napolitane"
            },
            {
               "Pizza":"Margarita"
            }
         ]
      }
   ]
}

Answer 1

问题出在JSONArray arr = new JSONArray(dbResult); 将其更改为JSONObject arr = new JSONObject(dbResult); 看来您还没有发布完整的 json 数据。如果没有解决，请发布完整的json data。

Answer 2

您从 db 获取 JSONObject，而不是数组，该数组位于该对象内部。您应该将来自 Web 服务的响应映射到 JSONObject，并将 bestelling 字段映射到 JSONArray。并且..正如评论中提到的，使用一些库来帮助你，比如 GSON。