سؤال

I have android class to parse a JSON array like this, Now the problem is it is only parsing 'image_first' index i want to parse 'image_second' too. But when i try to parse image_second it will throw some exceptions

code

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;



public class MainActivity extends Activity {

    EditText etResponse;
    TextView tvIsConnected;
    JSONObject jObject;
    JSONArray jCountries = null;
    String image_first;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // get reference to the views
        etResponse = (EditText) findViewById(R.id.etResponse);
        tvIsConnected = (TextView) findViewById(R.id.tvIsConnected);

        // check if you are connected or not
        if(isConnected()){
            tvIsConnected.setBackgroundColor(0xFF00CC00);
            tvIsConnected.setText("You are conncted");
        }
        else{
            tvIsConnected.setText("You are NOT conncted");
        }


        // call AsynTask to perform network operation on separate thread
        new HttpAsyncTask().execute("http://kodspider.com/Android_Test/index.php"/*"http://hmkcode.appspot.com/rest/controller/get.json"*/);
    }

    public static String GET(String url){
        InputStream inputStream = null;
        String result = "";
        try {

            // create HttpClient
            HttpClient httpclient = new DefaultHttpClient();

            // make GET request to the given URL
            HttpResponse httpResponse = httpclient.execute(new HttpGet(url));

            // receive response as inputStream
            inputStream = httpResponse.getEntity().getContent();

            // convert inputstream to string
            if(inputStream != null)
                result = convertInputStreamToString(inputStream);
            else
                result = "Did not work!";

        } catch (Exception e) {
            Log.d("InputStream", e.getLocalizedMessage());
        }

        return result;
    }

    private static String convertInputStreamToString(InputStream inputStream) throws IOException{
        BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
        String line = "";
        String result = "";
        while((line = bufferedReader.readLine()) != null)
            result += line;

        inputStream.close();
        return result;

    }

    public boolean isConnected(){
        ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
            if (networkInfo != null && networkInfo.isConnected()) 
                return true;
            else
                return false;   
    }
    private class HttpAsyncTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {

            return GET(urls[0]);
        }
        // onPostExecute displays the results of the AsyncTask.
        @Override
        protected void onPostExecute(String result) {
            Toast.makeText(getBaseContext(), "Received!", Toast.LENGTH_LONG).show();
            try {
                JSONObject json = new JSONObject(result);

                String str = "";

                JSONArray articles = json.getJSONArray("images");
                str += "articles length = "+json.getJSONArray("images").length();
                str += "\n--------\n";
                str += "names: "+articles.getJSONObject(0).names();
                str += "\n--------\n";
                str += "url: "+articles.getJSONObject(0).getString("image_second");

                etResponse.setText(str);
                etResponse.setText(json.toString(1));

                for(int i=0;i<json.getJSONArray("images").length();i++){

                System.out.println(articles.getJSONObject(i).getString("image_second"));

                }


//              try {
//                  jObject = new JSONObject(result);
//                  // Retrieves all the elements in the 'countries' array 
//                  jCountries = jObject.getJSONArray("images");
//                  for(int i=0;i<jCountries.length();i++){
//                   image_first = jCountries.getJSONObject(i).getString("image_first");
//                  }
//                  System.out.println(image_first);
//              } catch (JSONException e) {
//                  e.printStackTrace();
//              }



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

                }
       }
    }
}

logcat

05-14 12:19:15.700: W/System.err(581): org.json.JSONException: No value for image_second
05-14 12:19:15.700: W/System.err(581):  at org.json.JSONObject.get(JSONObject.java:354)
05-14 12:19:15.700: W/System.err(581):  at org.json.JSONObject.getString(JSONObject.java:510)
05-14 12:19:15.700: W/System.err(581):  at com.hmkcode.android.MainActivity$HttpAsyncTask.onPostExecute(MainActivity.java:125)
05-14 12:19:15.710: W/System.err(581):  at com.hmkcode.android.MainActivity$HttpAsyncTask.onPostExecute(MainActivity.java:1)
05-14 12:19:15.710: W/System.err(581):  at android.os.AsyncTask.finish(AsyncTask.java:417)
05-14 12:19:15.710: W/System.err(581):  at android.os.AsyncTask.access$300(AsyncTask.java:127)
05-14 12:19:15.710: W/System.err(581):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
05-14 12:19:15.720: W/System.err(581):  at android.os.Handler.dispatchMessage(Handler.java:99)
05-14 12:19:15.720: W/System.err(581):  at android.os.Looper.loop(Looper.java:123)
05-14 12:19:15.720: W/System.err(581):  at android.app.ActivityThread.main(ActivityThread.java:4627)
05-14 12:19:15.720: W/System.err(581):  at java.lang.reflect.Method.invokeNative(Native Method)
05-14 12:19:15.730: W/System.err(581):  at java.lang.reflect.Method.invoke(Method.java:521)
05-14 12:19:15.730: W/System.err(581):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-14 12:19:15.730: W/System.err(581):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-14 12:19:15.730: W/System.err(581):  at dalvik.system.NativeStart.main(Native Method)
هل كانت مفيدة؟

المحلول

Try to replace this line :

str += "url: "+articles.getJSONObject(0).getString("image_second");

With this :

str += "url: "+articles.getJSONObject(2).getString("image_second");

OR

str += "url: "+articles.getJSONObject(3).getString("image_second");

نصائح أخرى

{
    "images": [
        {
            "image_first": "http://kodspider.com/Android_Test/images/bg.jpg"
        },
        {
            "image_first": "http://kodspider.com/Android_Test/images/gmail_bg.jpg"
        },
        {
            "image_second": "http://kodspider.com/Android_Test/images/bbg.jpg"
        },
        {
            "image_second": "http://kodspider.com/Android_Test/images/1425328_405486846250283_806381377_o.jpg"
        }
    ]
}

Change this

for(int i=0;i<json.getJSONArray("images").length();i++){

            System.out.println(articles.getJSONObject(i).getString("image_second"));

}

To

JSONArray articles = json.getJSONArray("images");
JSONObject jb = articles.getJSONObject(0);
String imageurl1 = jb.getString("image_first");
JSONObject jb1 = articles.getJSONObject(1);
String imageurl2 = jb1.getString("image_first");
JSONObject jb2 = articles.getJSONObject(2);
String imageurl3 = jb2.getString("image_second");
JSONObject jb3 = articles.getJSONObject(3);
String imageurl4 = jb3.getString("image_second");
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