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我使用asynctask從URL下載JSON數據並將其傳遞給新活動需要解析並填充listview，但在下載應用程序崩潰後，在日誌聊天中表示它將canot轉換字符串到JSON對象，這裏是濺活動的代碼Android JSONObject問題
public class Init extends Activity {
static final String DEFAULT_URL = "http://api.androidhive.info/music/music.xml";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.init);
WebView loader = (WebView) findViewById(R.id.loader);
loader.loadUrl("file:///android_asset/index.html");
new LoadingTask().execute(DEFAULT_URL);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
public class LoadingTask extends AsyncTask<String, Object, Object>{
XMLParser parser = new XMLParser();
JSONParser jParser = new JSONParser();
@Override
protected Object doInBackground(String... params) {
// TODO Auto-generated method stub
String URL = params[0];
JSONObject json = jParser.getJSONFromUrl(URL);
//String xml = parser.getXmlFromUrl(URL); // getting XML from URL
// getting DOM element
return json;
}
protected void onPostExecute(Object result){
Intent startApp = new Intent("com.example.androidhive.HOME");
startApp.putExtra("json", result.toString());
startActivity(startApp);
//finish();
}
}
}
這是主要的活性源
public class Home extends Activity {
// All static variables
// XML node keys
static final String KEY_SONG = "song"; // parent node
static final String KEY_ID = "id";
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";
static final String KEY_DURATION = "duration";
static final String KEY_THUMB_URL = "thumb_url";
public static final String TAG_NEWS = "news";
public static final String TAG_ID = "id";
public static final String TAG_TITLE = "title";
public static final String TAG_STORY = "story";
public static final String TAG_SH_STORY = "shorten";
public static final String TAG_DATETIME = "datetime";
public static final String TAG_AUTHOR = "author";
public static final String TAG_IMG = "img";
ListView list;
LazyAdapter adapter;
Button mBtnNaslovnica;
private ViewSwitcher viewSwitcher;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
mBtnNaslovnica = (Button) findViewById(R.id.mBtnNaslovnica);
mBtnNaslovnica.setSelected(true);
TextView txtView=(TextView) findViewById(R.id.scroller);
txtView.setSelected(true);
ArrayList<HashMap<String, String>> homeList = new ArrayList<HashMap<String, String>>();
JSONObject jsonobj;
try {
jsonobj = new JSONObject(getIntent().getStringExtra("json"));
JSONArray news = jsonobj.getJSONArray(TAG_NEWS);
for(int i = 0; i < news.length(); i++){
JSONObject c = news.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_ID);
String title = c.getString(TAG_TITLE);
String story = c.getString(TAG_STORY);
String shorten = c.getString(TAG_SH_STORY);
String author = c.getString(TAG_AUTHOR);
String datetime = c.getString(TAG_DATETIME);
String img = c.getString(TAG_IMG);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_ID, id);
map.put(TAG_TITLE, title);
map.put(TAG_SH_STORY, shorten);
map.put(TAG_IMG, img);
map.put(TAG_AUTHOR, author);
// adding HashList to ArrayList
homeList.add(map);}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
list=(ListView)findViewById(R.id.list);
// Getting adapter by passing xml data ArrayList
adapter=new LazyAdapter(this, homeList);
list.setAdapter(adapter);
// Click event for single list row
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
String cur_title = ((TextView) view.findViewById(R.id.title)).getText().toString();
String cur_artis = ((TextView) view.findViewById(R.id.artist)).getText().toString();
String cur_duration = ((TextView) view.findViewById(R.id.duration)).getText().toString();
ImageView cur_img = (ImageView) view.findViewById(R.id.list_image);
String cur_img_url = (String) cur_img.getTag();
Intent i = new Intent("com.example.androidhive.CURENTNEWS");
i.putExtra("CUR_TITLE", cur_title);
i.putExtra("CUR_ARTIS", cur_artis);
i.putExtra("CUR_DURATION", cur_duration);
i.putExtra("CUR_IMG_URL", cur_img_url);
startActivity(i);
}
});
}
}
這是類的源保持適配器
public class LazyAdapter extends BaseAdapter {
private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader;
public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
activity = a;
data=d;
inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
imageLoader=new ImageLoader(activity.getApplicationContext());
}
public int getCount() {
return data.size();
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
View vi=convertView;
if(convertView==null)
vi = inflater.inflate(R.layout.list_row, null);
TextView title = (TextView)vi.findViewById(R.id.title); // title
TextView artist = (TextView)vi.findViewById(R.id.artist); // artist name
TextView duration = (TextView)vi.findViewById(R.id.duration); // duration
ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); // thumb image
HashMap<String, String> n = new HashMap<String, String>();
n = data.get(position);
// Setting all values in listview
title.setText(n.get(Home.TAG_TITLE));
artist.setText(n.get(Home.TAG_AUTHOR));
duration.setText(n.get(Home.TAG_DATETIME));
thumb_image.setTag(n.get(Home.TAG_IMG));
imageLoader.DisplayImage(n.get(Home.TAG_IMG), thumb_image);
return vi;
}
}
，這裏是logchat
08-31 14:34:41.066: V/xcli2(2349): DnsResolver.createDnsResolver() ok in run of WebCoreThread
08-31 14:34:42.546: E/JSON Parser(2349): Error parsing data org.json.JSONException: Value <?xml of type java.lang.String cannot be converted to JSONObject
08-31 14:34:42.546: W/dalvikvm(2349): threadid=1: thread exiting with uncaught exception (group=0x400207d8)
08-31 14:34:42.546: E/AndroidRuntime(2349): FATAL EXCEPTION: main
08-31 14:34:42.546: E/AndroidRuntime(2349): java.lang.NullPointerException
08-31 14:34:42.546: E/AndroidRuntime(2349): at com.example.androidhive.Init$LoadingTask.onPostExecute(Init.java:58)
08-31 14:34:42.546: E/AndroidRuntime(2349): at android.os.AsyncTask.finish(AsyncTask.java:417)
08-31 14:34:42.546: E/AndroidRuntime(2349): at android.os.AsyncTask.access$300(AsyncTask.java:127)
08-31 14:34:42.546: E/AndroidRuntime(2349): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
08-31 14:34:42.546: E/AndroidRuntime(2349): at android.os.Handler.dispatchMessage(Handler.java:99)
08-31 14:34:42.546: E/AndroidRuntime(2349): at android.os.Looper.loop(Looper.java:123)
08-31 14:34:42.546: E/AndroidRuntime(2349): at android.app.ActivityThread.main(ActivityThread.java:4645)
08-31 14:34:42.546: E/AndroidRuntime(2349): at java.lang.reflect.Method.invokeNative(Native Method)
08-31 14:34:42.546: E/AndroidRuntime(2349): at java.lang.reflect.Method.invoke(Method.java:521)
08-31 14:34:42.546: E/AndroidRuntime(2349): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
08-31 14:34:42.546: E/AndroidRuntime(2349): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:636)
08-31 14:34:42.546: E/AndroidRuntime(2349): at dalvik.system.NativeStart.main(Native Method)
您的網址是一個XML文檔不JSON –