CODEWITHSUNDEEP
javaandroidxmlparsingnullpointerexception
afsane
afsane

Reputation: 1919

java.lang.NullPointerException xml parsing

this code should parse the xml and show it ! but it has exeption :

02-02 12:36:49.508: I/Choreographer(1184): Skipped 32 frames! The application may be doing too much work on its main thread. 02-02 12:36:50.926: W/System.err(1184): java.lang.NullPointerException 02-02 12:36:50.926: W/System.err(1184): at com.example.sample.itcuties.android.reader.ITCutiesReaderAppActivity.onCreate(ITCutiesReaderAppActivity.java:52) 02-02 12:36:50.946: W/System.err(1184): at android.app.Activity.performCreate(Activity.java:5008) 02-02 12:36:50.946: W/System.err(1184): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 02-02 12:36:50.946: W/System.err(1184): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 02-02 12:36:50.966: W/System.err(1184): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 02-02 12:36:50.966: W/System.err(1184): at android.app.ActivityThread.access$600(ActivityThread.java:130) 02-02 12:36:50.986: W/System.err(1184): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 02-02 12:36:50.986: W/System.err(1184): at android.os.Handler.dispatchMessage(Handler.java:99) 02-02 12:36:50.998: W/System.err(1184): at android.os.Looper.loop(Looper.java:137) 02-02 12:36:51.006: W/System.err(1184): at android.app.ActivityThread.main(ActivityThread.java:4745) 02-02 12:36:51.018: W/System.err(1184): at java.lang.reflect.Method.invokeNative(Native Method) 02-02 12:36:51.026: W/System.err(1184): at java.lang.reflect.Method.invoke(Method.java:511) 02-02 12:36:51.026: W/System.err(1184): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 02-02 12:36:51.036: W/System.err(1184): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 02-02 12:36:51.036: W/System.err(1184): at dalvik.system.NativeStart.main(Native Method) 02-02 12:36:51.046: I/System.out(1184): xml activity Excpetion = java.lang.NullPointerException 02-02 12:36:51.736: I/Choreographer(1184): Skipped 39 frames! The application may be doing too much work on its main thread. 02-02 12:36:53.596: D/dalvikvm(1184): GC_CONCURRENT freed 180K, 4% free 8234K/8519K, paused 96ms+114ms, total 356ms

I cant find the reason!!!!

package com.example.sample.itcuties.android.reader;


import java.net.URL;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.TextView;


/**
 * Main application activity.
 * 
 * @author ITCuties
 *
 */
public class ITCutiesReaderAppActivity extends Activity {
    NodeList nodeList;
    /** 
     * This method creates main application view
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Set view

        try{


        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.HORIZONTAL);
         /** Create a new textview array to display the results */
        TextView name[];
        TextView website[];
        TextView category[];

        LongOperation lOp = new LongOperation(this);
        lOp.execute("");

         if(nodeList.getLength() > 0)
         {
             name = new TextView[nodeList.getLength()];
            website = new TextView[nodeList.getLength()];
            category = new TextView[nodeList.getLength()];

            for (int i = 0; i < nodeList.getLength(); i++) {

                Node node = nodeList.item(i);

                name[i] = new TextView(this);
                website[i] = new TextView(this);
                category[i] = new TextView(this);

                Element fstElmnt = (Element) node;
                NodeList nameList = fstElmnt.getElementsByTagName("name");
                Element nameElement = (Element) nameList.item(0);
                nameList = nameElement.getChildNodes();
                name[i].setText("Name = " + ((Node) nameList.item(0)).getNodeValue());

                NodeList websiteList = fstElmnt.getElementsByTagName("website");
                Element websiteElement = (Element) websiteList.item(0);
                websiteList = websiteElement.getChildNodes();
                website[i].setText("Website = " + ((Node) websiteList.item(0)).getNodeValue());

                category[i].setText("Website Category = " + websiteElement.getAttribute("category"));

                layout.addView(name[i]);
                layout.addView(website[i]);
                layout.addView(category[i]);
            }


         }

    /** Set the layout view to display */
            setContentView(layout);

         } catch (Exception e) {
             System.out.println("xml activity Excpetion = " + e);
         }
    }
     private class LongOperation extends AsyncTask<String, Void, String> {

         Context LongOperation;

            public LongOperation(Context context){
                   this.LongOperation = context;
                 }
            @Override
            protected String doInBackground(String... params) {


                try {

                    URL url = new URL("http://www.androidpeople.com/wp-content/uploads/2010/06/example.xml");
                    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                    DocumentBuilder db = dbf.newDocumentBuilder();
                    Document doc = db.parse(new InputSource(url.openStream()));
                    doc.getDocumentElement().normalize();

                    nodeList = doc.getElementsByTagName("item");

                } catch (Exception e) {
                    System.out.println("XML Pasing Excpetion = " + e);
                }


                return null;
            }        

            @Override
            protected void onPostExecute(String result) {             
            }

            @Override
            protected void onPreExecute() {
            }

            @Override
            protected void onProgressUpdate(Void... values) {
            }
        }

}

Upvotes: 0

Views: 711

Answers (1)

FD_
FD_

Reputation: 12919

LongOperation lOp = new LongOperation(this); lOp.execute("");

From this line, it seems you are filling nodeList in an AsyncTask, but instead of waiting for it to be filled, you start parsing it immediately. Make sure to start parsing from onPostExecuted in your LongOperation.

BTW, it would not be a bad idea to also do the parsing in the background.

Upvotes: 2

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