getJSONArray不工作optJSONArray返回null

Question

我正在尝试将JSON代码读入android应用程序。

JSON代码是：

{
 "query": {
  "count": 2,
  "created": "2014-05-07T21:08:55Z",
  "lang": "en-US",
  "diagnostics": {
   "publiclyCallable": "true",
   "url": [
    {
     "execution-start-time": "1",
     "execution-stop-time": "66",
     "execution-time": "65",
     "content": "http://www.datatables.org/yahoo/finance/quote/yahoo.finance.quote.xml"
    },
    {
     "execution-start-time": "70",
     "execution-stop-time": "179",
     "execution-time": "109",
     "content": "http://download.finance.yahoo.com/d/quotes.csv?f=aa2bb2b3b4cc1c3c6c8dd1d2ee1e7e8e9ghjkg1g3g4g5g6ii5j1j3j4j5j6k1k2k4k5ll1l2l3mm2m3m4m5m6m7m8nn4opp1p2p5p6qrr1r2r5r6r7ss1s7t1t7t8vv1v7ww1w4xy&s=BBVA"
    },
    {
     "execution-start-time": "2",
     "execution-stop-time": "572",
     "execution-time": "570",
     "content": "http://www.datatables.org/yahoo/finance/yahoo.finance.xchange.xml"
    },
    {
     "execution-start-time": "576",
     "execution-stop-time": "685",
     "execution-time": "109",
     "content": "http://download.finance.yahoo.com/d/quotes.csv?s=USDEUR=X&f=snl1d1t1ab"
    }
   ],
   "cache": [
    {
     "execution-start-time": "69",
     "execution-stop-time": "69",
     "execution-time": "0",
     "method": "GET",
     "type": "MEMCACHED",
     "content": "c7570b39f80748ad6afbbe8112eb8a8d"
    },
    {
     "execution-start-time": "576",
     "execution-stop-time": "576",
     "execution-time": "0",
     "method": "GET",
     "type": "MEMCACHED",
     "content": "71eb51553e3ee73f248dfdafabda5c44"
    }
   ],
   "query": [
    {
     "execution-start-time": "70",
     "execution-stop-time": "179",
     "execution-time": "109",
     "params": "{url=[http://download.finance.yahoo.com/d/quotes.csv?f=aa2bb2b3b4cc1c3c6c8dd1d2ee1e7e8e9ghjkg1g3g4g5g6ii5j1j3j4j5j6k1k2k4k5ll1l2l3mm2m3m4m5m6m7m8nn4opp1p2p5p6qrr1r2r5r6r7ss1s7t1t7t8vv1v7ww1w4xy&s=BBVA]}",
     "content": "select * from csv where url=@url and columns='Ask,AverageDailyVolume,Bid,AskRealtime,BidRealtime,BookValue,Change&PercentChange,Change,Commission,ChangeRealtime,AfterHoursChangeRealtime,DividendShare,LastTradeDate,TradeDate,EarningsShare,ErrorIndicationreturnedforsymbolchangedinvalid,EPSEstimateCurrentYear,EPSEstimateNextYear,EPSEstimateNextQuarter,DaysLow,DaysHigh,YearLow,YearHigh,HoldingsGainPercent,AnnualizedGain,HoldingsGain,HoldingsGainPercentRealtime,HoldingsGainRealtime,MoreInfo,OrderBookRealtime,MarketCapitalization,MarketCapRealtime,EBITDA,ChangeFromYearLow,PercentChangeFromYearLow,LastTradeRealtimeWithTime,ChangePercentRealtime,ChangeFromYearHigh,PercebtChangeFromYearHigh,LastTradeWithTime,LastTradePriceOnly,HighLimit,LowLimit,DaysRange,DaysRangeRealtime,FiftydayMovingAverage,TwoHundreddayMovingAverage,ChangeFromTwoHundreddayMovingAverage,PercentChangeFromTwoHundreddayMovingAverage,ChangeFromFiftydayMovingAverage,PercentChangeFromFiftydayMovingAverage,Name,Notes,Open,PreviousClose,PricePaid,ChangeinPercent,PriceSales,PriceBook,ExDividendDate,PERatio,DividendPayDate,PERatioRealtime,PEGRatio,PriceEPSEstimateCurrentYear,PriceEPSEstimateNextYear,Symbol,SharesOwned,ShortRatio,LastTradeTime,TickerTrend,OneyrTargetPrice,Volume,HoldingsValue,HoldingsValueRealtime,YearRange,DaysValueChange,DaysValueChangeRealtime,StockExchange,DividendYield'"
    },
    {
     "execution-start-time": "1",
     "execution-stop-time": "188",
     "execution-time": "187",
     "content": "\n    select * from yahoo.finance.quote where symbol in (\"BBVA\")"
    },
    {
     "execution-start-time": "576",
     "execution-stop-time": "685",
     "execution-time": "109",
     "content": "select * from csv where url='http://download.finance.yahoo.com/d/quotes.csv?s=USDEUR=X&f=snl1d1t1ab' and columns='Symbol,Name,Rate,Date,Time,Ask,Bid'"
    },
    {
     "execution-start-time": "1",
     "execution-stop-time": "686",
     "execution-time": "685",
     "content": "\n    select * from yahoo.finance.xchange where pair=\"USDEUR\"\n"
    }
   ],
   "javascript": [
    {
     "execution-start-time": "67",
     "execution-stop-time": "187",
     "execution-time": "119",
     "instructions-used": "56918",
     "table-name": "yahoo.finance.quote"
    },
    {
     "execution-start-time": "574",
     "execution-stop-time": "685",
     "execution-time": "110",
     "instructions-used": "75584",
     "table-name": "yahoo.finance.xchange"
    }
   ],
   "user-time": "686",
   "service-time": "853",
   "build-version": "0.2.2467"
  },
  "meta": {
   "meta": [
    null,
    null
   ]
  },
  "results": {
   "results": [
    {
     "quote": {
      "symbol": "BBVA",
      "AverageDailyVolume": "1436710",
      "Change": "+0.03",
      "DaysLow": "12.18",
      "DaysHigh": "12.32",
      "YearLow": "8.13",
      "YearHigh": "13.54",
      "MarketCapitalization": "71.052B",
      "LastTradePriceOnly": "12.28",
      "DaysRange": "12.18 - 12.32",
      "Name": "Banco Bilbao Vizc",
      "Symbol": "BBVA",
      "Volume": "959802",
      "StockExchange": "NYSE"
     }
    },
    {
     "rate": {
      "id": "USDEUR",
      "Name": "USD to EUR",
      "Rate": "0.7188",
      "Date": "5/7/2014",
      "Time": "5:05pm",
      "Ask": "0.7189",
      "Bid": "0.7188"
     }
    }
   ]
  }
 }
}

android的代码是：

公共类MainActivity扩展活动{

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());

    final TextView bolsa=(TextView)findViewById(R.id.bolsa);
    String resultado=busqueda();
    bolsa.append(resultado);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}
public static String busqueda()
{
    String devuelve=""; 
    HttpClient comunicacion=new DefaultHttpClient(); 

    HttpGet peticion=new HttpGet("http://query.yahooapis.com/v1/public/yql?q=SELECT%20*%20FROM%20yql.query.multi%20WHERE%20queries%3D%27%0A%20%20%20%20select%20*%20from%20yahoo.finance.quote%20where%20symbol%20in%20%28%22BBVA%22%29%3B%0A%20%20%20%20select%20*%20from%20yahoo.finance.xchange%20where%20pair%3D%22USDEUR%22%0A%27%3B&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&format=json");

    peticion.setHeader("content-type","application/json");



try
        {
            HttpResponse respuesta=comunicacion.execute(peticion);
            System.out.println("2");
            String respuestaCad=EntityUtils.toString(respuesta.getEntity());
            System.out.println("3");
        JSONObject respuestaJSON=new JSONObject(respuestaCad);
        System.out.println(respuestaJSON);

        JSONArray resultJSON=respuestaJSON.getJSONArray("results");
        System.out.println("4");

                    //JSONArray resultJSON=respuestaJSON.optJSONArray("results");


        String direccion="SIN DATOS";

        if(resultJSON.length()>0)
        {
            direccion=resultJSON.getJSONObject(0).getString("quote");
            System.out.println("5");
        }
        devuelve="Direccion: "+direccion;
    }

    catch(Exception e)
    {

        System.out.println("error");

    }
    return devuelve;
    }

}

我想读LastTradePriceOnly，但是getJSONArray方法不能工作(我看不到控制台中的System.out.println("4")。我看到一个例外)。我尝试过通过getJSONArray更改optJSONArray，但随后出现System.out.println("4")，然后resultJSON返回null。谢谢你的帮助。

Answer 1

按照上面提供的JSON，尝试下面的代码段。以后尝试使用http://json.parser.online.fr/进行进一步的联机JSON解析。

 try {

        HttpResponse respuesta=comunicacion.execute(peticion);
        System.out.println("2");
        String respuestaCad=EntityUtils.toString(respuesta.getEntity());
        System.out.println("3");
        JSONObject respuestaJSON=new JSONObject(respuestaCad);
        System.out.println(respuestaJSON);

    JSONObject respuestaJSON = new JSONObject(respuestaCad);
    System.out.println(respuestaJSON);

    JSONObject resultJSONObject = respuestaJSON.
            getJSONObject("query").getJSONObject("results");
    JSONArray resultJSON=resultJSONObject.getJSONArray("results");
        System.out.println("4");
 String direccion="SIN DATOS";

    if(resultJSON.length()>0)
    {
        direccion=resultJSON.getJSONObject(0).getString("quote");
        System.out.println("5");
    }
    devuelve="Direccion: "+direccion;

    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

Answer 2

结果数组位于JSONObject中。

尝试：

JSONArray resultJSON=respuestaJSON.getJSONObject ("results").getJSONArray("results");

Answer 3

像这样编辑你的代码。您必须先获得obecjct“结果”，然后才能得到“结果”数组。

    JSONObject respuestaJSON=new JSONObject(respuestaCad);
    System.out.println(respuestaJSON);
    JSONObject resultObject = respuestaJSON.getJSONObject("results");
    JSONArray resultJSON=resultObject.getJSONArray("results");
    System.out.println("4");

希望这会有所帮助:)