JSONObject不能连接到JSONArray-外部数据库

Question

我返回一个接受字符串值的JSONArray，但是每当我运行我的应用程序时，我都会得到下面的错误消息。我的（GetCityDetails）方法返回一个空值。下面是我的语法和logcat信息。我做错了什么？谢谢

@SuppressLint("NewApi")
public JSONArray GetCityDetails(String StateID) {

    @SuppressWarnings("deprecation")
    String url = "http://mywebsite.com/getCity.php?StateID="+URLEncoder.encode(StateID);

    HttpEntity httpEntity = null;

    try{

         DefaultHttpClient httpClient = new DefaultHttpClient();
         HttpGet httpGet = new HttpGet(url);

         HttpResponse httpResponse = httpClient.execute(httpGet);

         httpEntity = httpResponse.getEntity();


    } catch(ClientProtocolException e){
        e.printStackTrace();

    } catch(IOException e){
        e.printStackTrace();
    }


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

            InputStream entityResponse = httpEntity.getContent();
            String entityResponseAfterFunctionCall = convertInputStreamIntoString(entityResponse);

            Log.e("Entity Response From GetCityDetails Class: ", entityResponseAfterFunctionCall);

              jsonArray = new JSONArray(entityResponseAfterFunctionCall);
        } catch(JSONException e){
            e.printStackTrace();
        } catch(IOException e){
            e.printStackTrace();
        }
    }

    return jsonArray;
}

public String convertInputStreamIntoString(InputStream entityResponse) throws IOException{

    StringWriter writer = new StringWriter();
    IOUtils.copy(entityResponse, writer);
    String theString = writer.toString();
    return theString;
}


}

洛克卡特

01-01 19:11:36.719: E/Entity Response From GetCityDetails Class:(3938): null
01-01 19:11:36.729: W/System.err(3938): org.json.JSONException: Value null of type   org.json.JSONObject$1 cannot be converted to JSONArray
01-01 19:11:36.729: W/System.err(3938):     at org.json.JSON.typeMismatch(JSON.java:107)
01-01 19:11:36.729: W/System.err(3938):     at org.json.JSONArray.<init>(JSONArray.java:91)
01-01 19:11:36.729: W/System.err(3938):     at org.json.JSONArray.<init>(JSONArray.java:103)
01-01 19:11:36.729: W/System.err(3938):     at com.example.bhphprices.com.APIConnector.GetCityDetails(APIConnector.java:120)
01-01 19:11:36.729: W/System.err(3938):     at com.example.bhphprices.com.CityDetailsActivity$GetAllStates.doInBackground(CityDetailsActivity.java:64)
01-01 19:11:36.729: W/System.err(3938):     at  com.example.bhphprices.com.CityDetailsActivity$GetAllStates.doInBackground(CityDetailsActivity.java:1 )
01-01 19:11:36.739: W/System.err(3938):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
01-01 19:11:36.739: W/System.err(3938):     at    java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
01-01 19:11:36.739: W/System.err(3938):     at java.util.concurrent.FutureTask.run(FutureTask.java:138)
01-01 19:11:36.739: W/System.err(3938):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
01-01 19:11:36.739: W/System.err(3938):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
01-01 19:11:36.739: W/System.err(3938):     at java.lang.Thread.run(Thread.java:1019)

Answer 1

文档指出，可以通过传递集合或json格式的字符串来实例化JSONArray，但您传递的是一个空值，如日志的第一行所示。

我建议您调试ConvertinPutStreamintoString，并检查您的请求是否收到了错误的响应，还是有其他东西在获取字符串。