I cant call url xml parser

Question

my app get forclose, cant running with url have more caracter. im use xml parser for article in my app. if i call url like this ,my app force close.

   http://api.news.com/newsServices.asmx/getArticleByCategoryWithDetails?categoryname=nasional&start=0&limit=10

but if i call url like this, my app can running.

  http://api.news.com/news,Services.asmx/getArticle

this is my code :

   public class news extends Activity {

    private Activity activity;
    public ImageLoader imageLoader;

String URL = "http://api.news.com/newsServices.asmx/getArticleByCategoryWithDetails?categoryname=nasional&start=0&limit=10";
// XML node key

static final String KEY_ARTICLE = "Article"; // parent node
static final String KEY_ID = "ArticleID";
static final String KEY_AUTHOR = "Author";
static final String KEY_HEADLINE = "Headline";
static final String KEY_ARTICLEDATE = "ArticleDate";
static final String KEY_VIEWED = "Viewed";
static final String KEY_PUBLISHEDAT = "PublishedAt";
static final String KEY_SUMMARY = "Summary";
static final String KEY_BODY = "Body";
static final String KEY_IMAGEURL = "ImageURL";
static final String KEY_SLUG = "Slug";
static final String KEY_CATEGORY = "Category";


ListView list ;
LazyAdapter adapter;
private NodeList nl;
private xmlParser parser;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.news);

    activity = this;      

    ArrayList<HashMap<String, String>> songsList2 = new ArrayList<HashMap<String, String>>();

    parser = new xmlParser();
    String xml = parser.getXmlFromUrl(URL); // getting XML from URL
    Document doc = parser.getDomElement(xml); // getting DOM element

    Log.i("parser star", xml);

    nl = doc.getElementsByTagName(KEY_ARTICLE);
    // looping through all song nodes <song>
    for (int i = 1; i < nl.getLength(); i++) {
        // creating new HashMap
        HashMap<String, String> map = new HashMap<String, String>();
        Element e = (Element) nl.item(i);
        // adding each child node to HashMap key => value
        map.put(KEY_ID, parser.getValue(e, KEY_ID));
        map.put(KEY_HEADLINE, parser.getValue(e, KEY_HEADLINE));
        map.put(KEY_ARTICLEDATE, parser.getValue(e, KEY_ARTICLEDATE));
        map.put(KEY_IMAGEURL, parser.getValue(e, KEY_IMAGEURL));
        map.put(KEY_BODY, parser.getValue(e,KEY_BODY));

        // adding HashList to ArrayList
        songsList2.add(map);
    }

    list=(ListView)findViewById(R.id.list);


    // Getting adapter by passing xml data ArrayList
    adapter=new LazyAdapter(this, songsList2);          
    list.setAdapter(adapter);

logcat :

       12-19 09:40:06.154: E/Error:(30404): Unexpected token (position:TEXT Request format i...@2:1 in java.io.StringReader@413cc940) 
       12-19 09:40:06.154: I/parser star(30404): Request format is invalid: .
       12-19 09:40:06.154: D/AndroidRuntime(30404): Shutting down VM
       12-19 09:40:06.154: W/dalvikvm(30404): threadid=1: thread exiting with uncaught exception (group=0x40a991f8)
       12-19 09:40:06.154: E/AndroidRuntime(30404): FATAL EXCEPTION: main
       12-19 09:40:06.154: E/AndroidRuntime(30404): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.news/com.news.news}: java.lang.NullPointerException
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.ActivityThread.access$600(ActivityThread.java:123)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.os.Handler.dispatchMessage(Handler.java:99)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.os.Looper.loop(Looper.java:137)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.ActivityThread.main(ActivityThread.java:4424)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at java.lang.reflect.Method.invokeNative(Native Method)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at java.lang.reflect.Method.invoke(Method.java:511)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at dalvik.system.NativeStart.main(Native Method)
       12-19 09:40:06.154: E/AndroidRuntime(30404): Caused by: java.lang.NullPointerException
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at com.news.news.onCreate(news.java:80)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.Activity.performCreate(Activity.java:4465)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
       12-19 09:40:06.154: E/AndroidRuntime(30404):     ... 11 more

this is xml parser class

        public class xmlParser {

// constructor
public xmlParser() {

}

public String getXmlFromUrl(String url) {
    String xml = null;

    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        xml = EntityUtils.toString(httpEntity);

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    // return XML
    return xml;
}

public Document getDomElement(String xml){
    Document doc = null;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {

        DocumentBuilder db = dbf.newDocumentBuilder();

        InputSource is = new InputSource();
            is.setCharacterStream(new StringReader(xml));
            doc = db.parse(is); 

        } catch (ParserConfigurationException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (SAXException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (IOException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        }

        return doc;
}

 public final String getElementValue( Node elem ) {
     Node child;
     if( elem != null){
         if (elem.hasChildNodes()){
             for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
                 if( child.getNodeType() == Node.TEXT_NODE  ){
                     return child.getNodeValue();
                 }
             }
         }
     }
     return "";
 }


 public String getValue(Element item, String str) {     
        NodeList n = item.getElementsByTagName(str);        
        return this.getElementValue(n.item(0));
    }
     }