Reason for Null pointer Exception_问答_开发者_运维开发者技术经验分享

I cant figure out why my program is showing null pointer exception. Plz help me...Here's the program...

public class MusicListActivity extends Activity {
List<HashMap<String, String>> songNodeDet = new ArrayList<HashMap<String,String>>();
HashMap<?,?>[] songNodeWeb; 
XMLRPCClient client;
String logInSess;
ArrayList<String> paths=new ArrayList<String>();
public ListAdapter adapter ;
Object[] websongListObject;
List<SongsList> SngList=new ArrayList<SongsList>();
Runnable r;
ProgressDialog p;
ListView lv;
String s;
@Override
public void onCreate(Bundle si){
    super.onCreate(si);
    setContentView(R.layout.openadiuofile);
    lv=(ListView)findViewById(R.id.list1);
    r=new Runnable(){
        public void run(){
            try{
                getSongs();
            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (XMLRPCException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    };      
        Thread t=new Thread(r,"background");
        t.start();  
        Log.e("***","process over");
}
@Override
protected void onResume() {
    // TODO Auto-generated method stub
      super.onResume();

}
    private Runnable returnRes = new Runnable() {
    @Override
    public void run() { 
        Log.d("handler","handler");  
            removeDialog(0);
          p.dismiss();
          list();
        }                
        };
public void list()
{      Log.d("#####","#####");
 LayoutInflater inflater=getLayoutInflater();
 String[] from={};
 int[] n={};
 adapter=new SongsAdapter(getApplicationContext(),songNodeDet,R.layout.row,from,n,inflater);
 lv.setAdapter(adapter);}
private Handler handler = new Handler() {
    public void handleMessage(Message msg){
       Log.d("*****","handler");        
      removeDialog(0);
      p.dismiss();
     }
    }; 
 public void webObjectList(Object[] imgListObj,String logInSess) throws XMLRPCException{
    songNodeWeb = new HashMap<?,?>[imgListObj.length];
    if(imgListObj!=null){
        Log.e("completed","completed");
        for(int i=0;i<imgListObj.length;i++){ //imgListObj.length
        songNodeWeb[i]=(HashMap<?,?>)imgListObj[i];
        String nodeid=(String) songNodeWeb[i].get("nid");
        break;
        Log.e("img",i+"completed");
        HashMap<String,String> nData=new HashMap<String,String>();
        nData.put("nid",nodeid);        
        Object nodeget=client.call("node.get",logInSess,nodeid);
        HashMap<?,?> imgNode=(HashMap<?,?>)nodeget;
        String titleName=(String) imgNode.get("titles");
        String movieName=(String) imgNode.get("album");
        String singerName=(String) imgNode.get("artist");
        nData.put("titles", titleName);
        nData.put("album", movieName);
        nData.put("artist", singerName);
        Object[]  imgObject=(Object[])imgNode.get("field_image");
        HashMap<?,?>[] imgDetails=new HashMap<?,?>[imgObject.length];
        imgDetails[0]=(HashMap<?, ?>)imgObject[0];
        String path=(String) imgDetails[0].get("filepath");
        if(path.contains(" ")){
            path=path.replace(" ", "%20");
        }
         String imgPath="http://www.gorinka.com/"+path;
         paths.add(imgPath);
        nData.put("path", imgPath);
        Log.e("my path",path);
        String mime=(String)imgDetails[0].get("filemime");
        nData.put("mime", mime);
        SongsList songs=new SongsList(titleName,movieName,singerName,imgPath,imgPath);
        SngList.add(i,songs);
        songNodeDet.add(i,nData);
    }
    Log.e("paths values",paths.toString());     
//  return imgNodeDet;
    handler.sendEmptyMessage(0);
}
  }
    public void getSongs() throws MalformedURLException, XMLRPCException
{  
    String ur="http://www.gorinka.com/?q=services/xmlrpc";
    URL u=new URL(ur);
     client = new XMLRPCClient(u);      
    //Connecting to the website
    HashMap<?, ?> siteConn =(HashMap<?, ?>)  client.call("system.connect");
    // Getting initial sessio id
    String initSess=(String)siteConn.get("sessid");
    //Login to the site using session id        
    HashMap<?, ?> logInConn =(HashMap<?, ?>)  client.call("user.login",initSess,"prakash","stellentsoft2009");
    //Getting Login sessid
    logInSess=(String)logInConn.get("sessid");
    websongListObject =(Object[]) client.call("nodetype.get",logInSess,"");
     webObjectList(websongListObject,logInSess);
     Log.d("webObjectList","webObjectList");
     runOnUiThread(returnRes);
}

}

Here's the Adapter associated...

public class SongsAdapter extends SimpleAdapter{
static List<HashMap<String,String>> songsList;
Context context;
LayoutInflater inflater;
public SongsAdapter(Context context,List<HashMap<String,String>> imgListWeb,int layout,String[] from,int[] to,LayoutInflater inflater) {
    super(context,songsList,layout,from,to);
    this.songsList=songsList;
    this.context=context;
    this.inflater=inflater;
    // TODO Auto-generated constructor stub
}
@Override
public View getView(int postition,View convertView,ViewGroup parent)throws java.lang.OutOfMemoryError{
    try {
    View v = ((LayoutInflater) inflater).inflate(R.layout.row,null);
    ImageView images=(ImageView)v.findViewById(R.id.image);
    TextView tvTitle=(TextView)v.findViewById(R.id.text1);
    TextView tvAlbum=(TextView)v.findViewById(R.id.text2);
    TextView tvArt开发者_如何学JAVAist=(TextView)v.findViewById(R.id.text3);
    HashMap<String,String> songsHash=songsList.get(postition);
    String path=songsHash.get("path");
    String title=songsHash.get("title");
    String album=songsHash.get("album");
    String artist=songsHash.get("artist");
    String imgPath=path;    
    final ImageView imageView = (ImageView) v.findViewById(R.id.image);
    AsyncImageLoaderv asyncImageLoader=new AsyncImageLoaderv();
    Bitmap cachedImage = asyncImageLoader.loadDrawable(imgPath, new AsyncImageLoaderv.ImageCallback() {
        public void imageLoaded(Bitmap imageDrawable, String imageUrl) {
            imageView.setImageBitmap(imageDrawable);
        }
        });
    imageView.setImageBitmap(cachedImage);
    tvTitle.setText(title);
    tvAlbum.setText(album);
    tvArtist.setText(artist);
    return v;
    }
    catch(Exception e){
        Log.e("error",e.toString());
    }
    return null;
}
public static Bitmap loadImageFromUrl(String url) {
    InputStream inputStream;Bitmap b;
try {
    inputStream = (InputStream) new URL(url).getContent();
    BitmapFactory.Options bpo=  new BitmapFactory.Options();
    bpo.inSampleSize=2;
     b=BitmapFactory.decodeStream(inputStream, null,bpo );
     return b;
} catch (IOException e) {
        throw new RuntimeException(e);
    }
}

}

Here is what logcat is showing...

04-23 16:02:02.211: ERROR/completed(1450): completed
04-23 16:02:02.211: ERROR/paths values(1450): []
04-23 16:02:02.211: DEBUG/*****(1450): handler
04-23 16:02:02.211: DEBUG/AndroidRuntime(1450): Shutting down VM
04-23 16:02:02.211: WARN/dalvikvm(1450): threadid=3: thread exiting with uncaught exception (group=0x4001aa28)
04-23 16:02:02.222: ERROR/AndroidRuntime(1450): Uncaught handler: thread main exiting due to uncaught exception
04-23 16:02:02.241: DEBUG/webObjectList(1450): webObjectList
04-23 16:02:02.252: ERROR/AndroidRuntime(1450): java.lang.NullPointerException
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at com.stellent.gorinka.MusicListActivity$2.handleMessage(MusicListActivity.java:81)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at android.os.Looper.loop(Looper.java:123)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at android.app.ActivityThread.main(ActivityThread.java:4203)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at java.lang.reflect.Method.invokeNative(Native Method)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at java.lang.reflect.Method.invoke(Method.java:521)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
04-23 16:02:02.252: ERROR/AndroidRuntime(1450):     at dalvik.system.NativeStart.main(Native Method)

I have declared the getter and setter methods in a seperate claa named SongsList. Plz help me determine the problem...

ProgressDialog p seems to be null when your Handler handler's handleMessage is called. I cannot see any code where you assign something to p, so I'm guessing the error is there...