无法从服务器

Question

得到JSON文件我想下面的JSON数据库解析为我的Android应用

[ 
    { 
    "name": "Bitcoin", 
    "symbol": "BTC", 
    "price_usd": 4075.51, 
    "price_eur": 3468.74399569, 
    "price_btc": 1, 
    "volume_eur": 2212237015.99, 
    "market_cap_usd": 67303991018, 
    "percent_change_1h": -1.33, 
    "percent_change_24h": -5.7, 
    "percent_change_7d": 14.06 
    }, 
    { 
    "name": "district0x", 
    "symbol": "DNT", 
    "price_usd": 0.155491, 
    "price_eur": 0.1323413444, 
    "price_btc": 0.00003828, 
    "volume_eur": 4358137.81712, 
    "market_cap_usd": 93294600, 
    "percent_change_1h": -2.65, 
    "percent_change_24h": 17.31, 
    "percent_change_7d": 91.52 
    }, 
    { 
    "name": "Ethereum", 
    "symbol": "ETH", 
    "price_usd": 295.651, 
    "price_eur": 251.634183469, 
    "price_btc": 0.0727828, 
    "volume_eur": 735525975.253, 
    "market_cap_usd": 27812727380, 
    "percent_change_1h": -0.65, 
    "percent_change_24h": -2.57, 
    "percent_change_7d": -2.83 
    } 
] 

用下面的代码：

protected Void doInBackground(Void... arg0) { 
     databasehandler sh = new databasehandler(); 

     // Making a request to url and getting response 
     String jsonStr = sh.makeServiceCall(url); 

     Log.e(TAG, "Response from url: " + jsonStr); 

     if (jsonStr != null) { 
      try { 
       JSONArray jsonArray = new JSONArray(jsonStr); 

       // Getting JSON Array node 
       JSONArray currencies = jsonArray.getJSONArray(0); 

       // looping through currencies 
       for (int i = 0; i < currencies.length(); i++) { 
        JSONObject c = currencies.getJSONObject(i); 

        String name = c.getString("name"); 
        String symbol = c.getString("symbol"); 
        String price_usd = c.getString("price_usd"); 
        String price_eur = c.getString("price_eur"); 
        String price_btc = c.getString("price_btc"); 
        String volume_eur = c.getString("volume_eur"); 
        String market_cap_usd = c.getString("market_cap_usd"); 
        String percent_change_1h = c.getString("percent_change_1h"); 
        String percent_change_24h = c.getString("percent_change_24h"); 
        String percent_change_7d = c.getString("percent_change_7d"); 


        // tmp hash map for single contact 
        HashMap<String, String> currency = new HashMap<>(); 

        // adding each child node to HashMap key => value 

        currency.put("name", name); 
        currency.put("symbol", symbol); 

        // adding currency to currencyList 
        currencyList.add(currency); 
       } 
      } catch (final JSONException e) { 
       Log.e(TAG, "Json parsing error: " + e.getMessage()); 
       runOnUiThread(new Runnable() { 
        @Override 
        public void run() { 
         Toast.makeText(getApplicationContext(), 
           "Json parsing error: " + e.getMessage(), 
           Toast.LENGTH_LONG) 
           .show(); 
        } 
       }); 

      } 

}

不知怎的，我可以从服务器获取这些数据并且我的LogCat日志中说明如下：

08-15 13：49：07.751 25055-25055 /？ E/PGA：PgaSocketInitClientPgaIpc： ioctl（）失败：ret -1，errno 22 08-15 13：49：07.761 25055-25055 /？ I/PGA：PgaSocketInitPgaIpc：打开/ dev/bstpgaipc：fd = 14 08-15 13：49：07.761 25055-25055 /？ I/PGA：试图创建新的套接字 connectionn PID = 25055，TID = 25055

编辑：

这里是数据库处理器类

public class databasehandler { 
    private static final String TAG = databasehandler.class.getSimpleName(); 

    public String makeServiceCall(String reqUrl) { 
     String response = null; 
     try { 
      URL url = new URL(reqUrl); 
      HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
      conn.setRequestMethod("GET"); 
      // read the response 
      InputStream in = new BufferedInputStream(conn.getInputStream()); 
      response = convertStreamToString(in); 
     } catch (MalformedURLException e) { 
      Log.e(TAG, "MalformedURLException: " + e.getMessage()); 
     } catch (ProtocolException e) { 
      Log.e(TAG, "ProtocolException: " + e.getMessage()); 
     } catch (IOException e) { 
      Log.e(TAG, "IOException: " + e.getMessage()); 
     } catch (Exception e) { 
      Log.e(TAG, "Exception: " + e.getMessage()); 
     } 
     return response; 
    } 

    private String convertStreamToString(InputStream is) { 
     BufferedReader reader = new BufferedReader(new InputStreamReader(is)); 
     StringBuilder sb = new StringBuilder(); 

     String line; 
     try { 
      while ((line = reader.readLine()) != null) { 
       sb.append(line).append('\n'); 
      } 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } finally { 
      try { 
       is.close(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } 
     } 
     return sb.toString(); 
    } 

} 

Answer 1

删除此行

JSONArray currencies = jsonArray.getJSONArray(0); 

and use jsonArray in

for (int i = 0; i < jsonArray.length(); i++) { 
    JSONObject c = jsonArray.getJSONObject(i); 
}