Android JSONObject结果始终为null？

Question

I'm new to Android and JSON and I'm attempting to retrieve some JSON data from yahoo's weather service, and .setText in three of my textviews in my xml to the relevant data in the JSON object

This is where I'm getting the rest query (Hit test and you'll get the rest query):

https://developer.yahoo.com/yql/console/#h=select+*+from+weather.forecast+where+woeid%3D2502265

Error:

12-22 19:39:10.745  31404-31431/eggy.com.jsontest E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
    Process: eggy.com.jsontest, PID: 31404
    java.lang.RuntimeException: An error occured while executing doInBackground()
            at android.os.AsyncTask$3.done(AsyncTask.java:300)
            at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
            at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
            at java.util.concurrent.FutureTask.run(FutureTask.java:242)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)
     Caused by: java.lang.NullPointerException
            at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
            at org.json.JSONTokener.nextValue(JSONTokener.java:94)
            at org.json.JSONObject.<init>(JSONObject.java:155)
            at org.json.JSONObject.<init>(JSONObject.java:172)
            at eggy.com.jsontest.MainActivity$MyAsyncTask.doInBackground(MainActivity.java:81)
            at eggy.com.jsontest.MainActivity$MyAsyncTask.doInBackground(MainActivity.java:41)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)

Code:

public class MainActivity extends ActionBarActivity {
    private static String yahooWeatherInfo =
           "https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20weather.forecast%20where%20woeid%3D2502265&format=json&diagnostics=true&callback=";
    private static String chill = "";
    private static String direction = "";
    private static String speed = "";

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

        private class MyAsyncTask extends AsyncTask<String,String,String> {

            @Override
            protected String doInBackground(String... params) {

                DefaultHttpClient  httpclient = new DefaultHttpClient(new BasicHttpParams());
                HttpPost httppost = new HttpPost(yahooWeatherInfo);

                // Depends on your web service
                httppost.setHeader("Content-type", "application/json");

                InputStream inputStream = null;
                String result = null;
                try {
                    HttpResponse response = httpclient.execute(httppost);
                    HttpEntity entity = response.getEntity();

                    inputStream = entity.getContent();
                    // json is UTF-8 by default
                    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
                    StringBuilder sb = new StringBuilder();

                    String line = null;
                    while ((line = reader.readLine()) != null)
                    {
                        sb.append(line + "\n");
                    }
                    result = sb.toString();
                } catch (Exception e) {
                    // Oops
                }
                finally {
                    try{
                        if(inputStream != null)
                            inputStream.close();
                    }catch(Exception squish){

                    }
                }
                try {
                    JSONObject jObject = new JSONObject(result);
                    JSONObject queryObject = jObject.getJSONObject("query");
                    JSONObject windObject = queryObject.getJSONObject("wind");
                    chill = windObject.getString("chill");
                    direction = windObject.getString("direction");
                    speed = windObject.getString("speed");
                } catch(JSONException e) {

                }
                return null;
            }
                    @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            TextView line1 = (TextView) findViewById(R.id.line1);
            TextView line2 = (TextView) findViewById(R.id.line2);
            TextView line3 = (TextView) findViewById(R.id.line3);
            line1.setText("Chill " + chill);
            line2.setText("Direction " + direction);
            line3.setText("Speed " + speed);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

The error is always at:

 JSONObject jObject = new JSONObject(result);

Maybe I'm using the wrong query, I'm not entirely sure.

Thank you for your help.

Answer 1

You are having an issue with the HTTP request for sure.

Google has made this process super simple using Volley, no more messy http requests needed. It will manage the request and return a proper object.

Read the docs here: https://developer.android.com/training/volley/simple.html

Answer 2

try this

JSONObject jObject = new JSONObject(result);
JSONObject windObject = jObject.getJSONObject("query").getJSONObject("results").getJSONObject("channel").getJSONObject("wind");

follow nested objects to JSON