我正试图在我的程序中压缩所有力量关闭，这是经常出现的一个：
java.lang.RuntimeException: An error occured while executing doInBackground()
android.os.AsyncTask$3.done(AsyncTask.java:200)
java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
java.util.concurrent.FutureTask.setException(FutureTask.java:124)
java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
java.util.concurrent.FutureTask.run(FutureTask.java:137)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
java.lang.Thread.run(Thread.java:1096) Caused by: java.lang.NullPointerException
org.json.JSONTokener.more(JSONTokener.java:98)
org.json.JSONTokener.next(JSONTokener.java:108)
org.json.JSONTokener.nextClean(JSONTokener.java:162)
org.json.JSONArray.(JSONArray.java:103)
org.json.JSONArray.(JSONArray.java:150)
com.appinfluence.musicpromotion.SongList$LoadList.doInBackground(SongList.java:969)
com.appinfluence.musicpromotion.SongList$LoadList.doInBackground(SongList.java:1)
android.os.AsyncTask$2.call(AsyncTask.java:185)
java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
这是正在运行的AsyncTask
private class LoadList extends AsyncTask<String, UserRecord, JSONArray> {
String result = null;
InputStream is = null;
StringBuilder sb = null;
String[] displayname = null;
String[] song_id = null;
String[] song_name = null;
String[] artist = null;
String[] description = null;
String[] genre = null;
String[] custom_genre = null;
String[] album = null;
String[] timestamp = null;
String[] avatar = null;
String[] section = null;
String[] plays = null;
String[] downloads = null;
String[] ratingcount = null;
String[] commentcount = null;
int[] dlFlag = null;
JSONArray jArray;
Float[] test_rating;
String[] songurl;
UserRecord user5;
String[] viewss;
String[] link1;
String[] link2;
String[] link3;
String[] link4;
String[] link5;
protected JSONArray doInBackground(String... link) {
linkurl = link[0];
URI uri = null;
try {
uri = new URI(link[0]);
} catch (URISyntaxException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(uri);
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection"+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"UTF8"),8);
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line="0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
try{
jArray = new JSONArray(result);
JSONObject json_data=null;
displayname = new String[jArray.length()];
song_name = new String[jArray.length()];
artist = new String[jArray.length()];
description = new String[jArray.length()];
genre = new String[jArray.length()];
custom_genre = new String[jArray.length()];
album = new String[jArray.length()];
timestamp = new String[jArray.length()];
song_id = new String[jArray.length()];
avatar = new String[jArray.length()];
test_rating = new Float[jArray.length()];
songurl = new String[jArray.length()];
viewss = new String[jArray.length()];
section = new String[jArray.length()];
plays = new String[jArray.length()];
downloads = new String[jArray.length()];
ratingcount = new String[jArray.length()];
commentcount = new String[jArray.length()];
dlFlag = new int[jArray.length()];
link1 = new String[jArray.length()];
link2 = new String[jArray.length()];
link3 = new String[jArray.length()];
link4 = new String[jArray.length()];
link5 = new String[jArray.length()];
for(int i=0;i<jArray.length();i++){
json_data = jArray.getJSONObject(i);
song_id[i]=json_data.getString("id");
song_name[i]=json_data.getString("songname");
artist[i]=json_data.getString("artist");
displayname[i]=json_data.getString("displayname");
description[i]=json_data.getString("description");
genre[i]=json_data.getString("genre");
custom_genre[i]=json_data.getString("customgenre");
album[i]=json_data.getString("album");
timestamp[i]=json_data.getString("format");
avatar[i]=json_data.getString("image_url");
songurl[i]=json_data.getString("song_url");
test_rating[i] = (float) json_data.getDouble("rating");
viewss[i] = json_data.getString("views");
section[i] = json_data.getString("section");
plays[i] = json_data.getString("plays");
downloads[i] = json_data.getString("downloads");
ratingcount[i] = json_data.getString("rating_count");
commentcount[i] = json_data.getString("comments");
dlFlag[i] = json_data.getInt("downloadflag");
link1[i] = json_data.getString("link1");
link2[i] = json_data.getString("link2");
link3[i] = json_data.getString("link3");
link4[i] = json_data.getString("link4");
link5[i] = json_data.getString("link5");
user5 = new UserRecord(genre[i], displayname[i], timestamp[i], test_rating[i], songurl[i], viewss[i], song_id[i], avatar[i], description[i], section[i], plays[i], downloads[i], ratingcount[i], commentcount[i], dlFlag[i], link1[i], link2[i], link3[i], link4[i], link5[i]);
publishProgress(user5);
}
}
catch(JSONException e1){
e1.printStackTrace();
} catch (ParseException e1) {
e1.printStackTrace();
}
return null;
}
protected void onProgressUpdate(UserRecord... progress) {
users.add(progress[0]);
}
protected void onPostExecute(JSONArray jArray) {
filter = 0;
loading = 0;
adapterz.notifyDataSetChanged();
if (dialog.isShowing()) {
dialog.dismiss();
}
limit = limit + 20;
listView.setOnScrollListener(new OnScrollListener(){
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
int lastInScreen = firstVisibleItem + visibleItemCount;
if (songcount.length != 0) {
if(lastInScreen == totalItemCount && loading == 0 && limit < songcount[0] && number != 55){
if (isNetworkAvailable() == false){
Toast toast = Toast.makeText(getApplicationContext(), "This app requires an internet connection", Toast.LENGTH_LONG);
toast.show();
} else {
new LoadList().execute(link2);
}
}
}
}
public void onScrollStateChanged(AbsListView view, int scrollState) {}
});
}
protected void onPreExecute(){
if (number == 2) {
if (isNetworkAvailable() == false){
Toast toast = Toast.makeText(getApplicationContext(), "This app requires an internet connection", Toast.LENGTH_LONG);
toast.show();
} else {
new SongCount().execute(genrecount);
}
} else {
if (isNetworkAvailable() == false){
Toast toast = Toast.makeText(getApplicationContext(), "This app requires an internet connection", Toast.LENGTH_LONG);
toast.show();
} else {
new SongCount().execute(songcountphp);
}
}
loading = 1;
if (filter == 1 || number == 55){
adapterz.clear();
}
limitstring = limit.toString();
nameValuePairs.add(new BasicNameValuePair("limit",limitstring));
dialog = ProgressDialog.show(SongList.this, "",
"Loading. Please wait...", true);
}
}
这就是它发生的那条线：
jArray = new JSONArray(result);
我怎样才能优雅地避免这种情况？谢谢！
答案 0 :(得分：0)
要优雅，你需要进行空检查，或者在那里捕获NullPointerException，然后优雅地包含一些方法来静静地重试提取，或者通知用户错误。
答案 1 :(得分：0)
jArray = new JSONObject(result);
JSONObject可以包含其他JSONObject或JSONArray的
有关详细信息，请参阅this链接。