I'm searching for a solution to preload some videos from different urls into VideoViews, so that they could be played without any delay.
I'm trying to do this in an async task:
class VideoPreloadTask extends AsyncTask<String, Void, Void> {
private Context mContext;
private CustomVideoView mVideoView;
public VideoPreloadTask(Context context) {
mContext = context;
}
#Override
public void onPreExecute() {
mVideoView = new CustomVideoView(mContext);
}
#Override
protected Void doInBackground(String... params) {
final String url = params[0];
mVideoView.setVideoPath(url);
mVideoView.setOnPreparedListener(new OnPreparedListener() {
//Wird aufgerufen, wenn das Video fertig geladen ist
#Override
public void onPrepared(MediaPlayer mp) {
mCounter++;
mVideoView.pause();
mVideoView.setPreloaded(true);
//Fuege das fertig geladene Video der Liste hinzu
mVideos.put(url, mVideoView);
}
});
mVideoView.start();
return null;
}
}
Now within the doInBackground-Method I set the path Url and start the loading of the video with start(). But the onPrepare-Listener does not work. The function never gets called and I don't understand why. I've tried loading some videos outside of an async task and it works well.
The async tasks are started like this:
for(String url : videoUrls) {
VideoPreloadTask task = new VideoPreloadTask(context);
task.execute(url);
}
and my CustomVideoView-Class looks like the following:
public class CustomVideoView extends VideoView {
private boolean mPreloaded = false;
private String mPath = "";
public CustomVideoView(final Context context) {
super(context);
}
public CustomVideoView(final Context context, final AttributeSet set) {
super(context, set);
}
#Override
public void setVideoPath(String url) {
super.setVideoPath(url);
mPath = url;
}
public boolean isPreloaded() {
return mPreloaded;
}
public void setPreloaded(boolean isPreloaded) {
mPreloaded = isPreloaded;
}
public String getVideoPath() {
return mPath;
}
}
Does anybody know, what causes this behaviour or where I've made a mistake?
Finally solved my problem. For everyone whos interested, heres the answer:
It seems as if Android only preloads the VideoViews video, when the view is part of an XML-Layout, which is also currently active. So if you want to preload a video, make the videoview part of your xml and do not create a videoview-object with the constructor, as I've done it.
Then it should work! :D
Related
I usually use AsyncTask in the same class with the caller, but now I want to call asyntask from different class using interface class,I want to get value from onProgressUpdate call from another clas, this my asynctask class..
class UploadFileToServer extends AsyncTask<String, Integer, String> implements DialogInterface.OnCancelListener {
private String url;
private File file;
ShareProgress shareProgres;
SharePosExecute sharePosExecute;
public UploadFileToServer(String url, String file) {
this.url = url;
this.file = new File(file);
}
#Override
protected void onPreExecute() {
}
#Override
protected String doInBackground(String... v) {
//place code of upload file to server,run very well...
return responseFromServer;
}
#Override
protected void onProgressUpdate(Integer... progress) {
Log.v("progress",progress[0]+""); //this work well
shareProgres.progressUpdate(progress[0]); //I get error in here
}
#Override
protected void onPostExecute(String response) {
sharePosExecute.posExecute(response); // i also get error in here
}
#Override
public void onCancel(DialogInterface dialog) {
cancel(true);
// dialog.dismiss();
}
}
in my activity class
public class myActivity extends SherlockFragmentActivity implements ShareProgress,SharePosExecute {
#Override
public void progressUpdate(int progress) {
Log.i("progress in myactivity",progress+""); //i want to this code work.
}
#Override
public void posExecute(String output) {
Log.i("processFinish myActivity",output);
}
}
I use interface class for comunicated with diferent class, here my interface code
public interface ShareProgress {
void progressUpdate(int progress);
}
how do i fix this,may be there is another ways for this, please help
thanks
you should be setting your Listener in your asynctask right?
ShareProgress shareProgres;
SharePosExecute sharePosExecute;
public UploadFileToServer(String url, String file,ShareProgress shareProgres,SharePosExecute sharePosExecute) {
this.url = url;
this.file = new File(file);
this.shareProgres=shareProgres;
this.sharePosExecute=sharePosExecute;
}
and in your activity,start initialize your async task:
UploadFileToServer uFTS=new UploadFileToServer(url,file,myActivity.this,myActivity.this);
//then execute:
uFTS.execute();
I want to generate a form into my activity_main.xml ScrollView. XML is loaded and parsed correctly but when I'm trying to addView(LinearLayout) then it throws exception e. My application gets url of a XML file via push notification and then parses it. According to XML it then should generate a form and display it to the user. I used this as an example: https://www.ibm.com/developerworks/xml/tutorials/x-andddyntut/#l1
Here is my main activity:
public class MainActivity extends Activity {
// label to display gcm messages
TextView lblMessage;
Controller aController;
public ScrollView sv;
Button execute;
// Asyntask
AsyncTask<Void, Void, Void> mRegisterTask;
public static String name;
public static String email;
final Context context = this;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ScrollView sv = (ScrollView) findViewById(R.id.sv);
...
}
// Create a broadcast receiver to get message and show on screen
private final BroadcastReceiver mHandleMessageReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String newMessage = intent.getExtras().getString(Config.EXTRA_MESSAGE);
// Waking up mobile if it is sleeping
aController.acquireWakeLock(getApplicationContext());
ScrollView sv = (ScrollView) findViewById(R.id.sv);
new DoInBackground(getApplicationContext(), sv).execute(newMessage);
// Releasing wake lock
aController.releaseWakeLock();
}
};
and here is my async class:
public class DoInBackground extends AsyncTask<String, Void, Void> {
Context mContext;
ScrollView mSv;
String tag = "DynamicFormXML";
XmlGuiForm theForm;
ProgressDialog progressDialog;
Handler progressHandler;
public DoInBackground(Context context, ScrollView sv) {
this.mContext = context;
this.mSv = sv;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(String... params) {
if (GetFormData(params[0])) {
DisplayForm();
}
else
{
Log.e(tag,"Couldn't parse the Form.");
AlertDialog.Builder bd = new AlertDialog.Builder(mContext);
AlertDialog ad = bd.create();
ad.setTitle("Error");
ad.setMessage("Could not parse the Form data");
ad.show();
}
return null;
}
protected void onPostExecute() {
}
private boolean DisplayForm()
{
try
{
final LinearLayout ll = new LinearLayout(mContext);
mSv.addView(ll); //Here it fails
ll.setOrientation(android.widget.LinearLayout.VERTICAL);
...
} catch (Exception e) { // Goes to here
Log.e(tag,"Error Displaying Form");
return false;
}
}
I think the context of the main activity and also the empty Scrollview in main activity are forwarded correctly (they are not null) but i'm not 100% sure. Any help/hints are appreciated! :)
You can not touch the GUI from a background thread (e.g. the one running the doInBackground method).
In an AsynTask, you can put the UI code in onPostExecute, wich is invoked on the UI thread with the result of doInBackground.
If you have intermediate results you can call publishProgress from doInBackground, this will trigger the invocation of onProgressUpdate on the UI thread, where you can update the UI.
See AsyncTask API for an example and more details on what must be done on which thread.
Solution
Reordering code (so GUI stuff would be done onPostExecute) worked. Also i had a problem with not getting to onPostExecute() but i had to change it to onPostExecute(Void result).
Now my code looks like this and works like a charm:
public class DoInBackground extends AsyncTask<String, Void, Void> {
Context mContext;
LinearLayout mLl;
String tag = "DynamicFormXML";
XmlGuiForm theForm;
ProgressDialog progressDialog;
Handler progressHandler;
public DoInBackground(Context context, LinearLayout ll) {
this.mContext = context;
this.mLl = ll;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(String... params) {
getFormData(params[0]);
return null;
}
protected void onPostExecute(Void result) {
DisplayForm();
}
I also added ScrollView and LinearLayout to my activity_main.xml so DisplayForm() looks like that (if you want to follow the example i mentioned before ):
private void DisplayForm() {
try
{
// walk thru our form elements and dynamically create them, leveraging our mini library of tools.
int i;
for (i=0;i<theForm.fields.size();i++) {
if (theForm.fields.elementAt(i).getType().equals("text")) {
theForm.fields.elementAt(i).obj = new XmlGuiEditBox(mContext,(theForm.fields.elementAt(i).isRequired() ? "*" : "") + theForm.fields.elementAt(i).getLabel(),"");
mLl.addView((View) theForm.fields.elementAt(i).obj);
}
...
I want download details from web and update the UI within the doInBackground(),
For that I think I must get reference to activity within that method .How can I do it or is there another way to do that? What must be the something parameter? Or can’t update UI real-time?
public class DownloadActivity extends ListActivity {
public class DownloadItems extends AsyncTask<Something,Integer,Long> {
#Override
protected Long doInBackground(DownloadActivity... params) {
Toast.makeText(params[0], getIntent().getExtras().get("location").toString(), Toast.LENGTH_SHORT).show();
return null;
}
}
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
new DownloadItems().execute(Something);
}
}
You can either use a Handler or update your UI in onPostExecute(), which I recommend. Let your Async take care of its background logic and update the UI when that work is finished.
The best way is to simply move anything which affects UI into onPostExecute() because it's there to allow you to update the UI, it's the point of it.
There are other ways but when using AsyncTask there's really no reason not to use this.
public class DownloadActivity extends ListActivity {
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
new DownloadItems(this).execute();
}
public class DownloadItems extends AsyncTask<Something,Integer,Long> {
private Context context;
public DownloadItems(Context c){
context = c;
}
#Override
protected Long doInBackground(DownloadActivity... params) {
// Do something
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
Toast.makeText(context, context.getIntent().getExtras().get("location").toString(), Toast.LENGTH_SHORT).show();
}
}
}
You can create a constructor for passing or adding Context as a parameter.
public class DownloadItems extends AsyncTask<Something,Integer,Long> {
Context context;
public DownloadItems(Context cntx){
context = cntx;
}
#Override
protected Long doInBackground(DownloadActivity... params) {
//Toast.makeText(params[0], getIntent().getExtras().get("location").toString(), Toast.LENGTH_SHORT).show();
Toast.makeText(context, "String test", Toast.LENGTH_SHORT).show();
return null;
}
}
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
new DownloadItems(this).execute(Something);
}
By passing the context of the activity you can make any operation that are context related.
You can't execute UI operations in doInBackground(), you must do them in onPostExecute(). In DownloadActivity, you will create an instance of DownloadItems, and pass it the url where you want to download your stuff :
For example :
public class DownloadActivity extends ListActivity {
private void someMethod() {
DownloadItems yourTask = new DownloadItems(getApplicationContext());
yourTask.execute(yourUrl);
}
In the AsyncTask, you will do your download operations in doInBackground() and return the result so it can be handled by onPostExecute() :
public class DownloadItems extends AsyncTask<Something,Integer,Long> {
Context mContext;
public DownloadItems(Context context){
mContext = context;
}
#Override
protected String doInBackground(String... params) {
String theResult;
// download operations using url stored in params[0], and where you set theResult variable (for example...)
return theResult;
}
In onPostExecute(), you deal with the result, for example in your code above, you can call the Toast :
#Override
protected void onPostExecute(String result) {
Toast.makeText("YOUR TAG", result, Toast.LENGTH_SHORT).show();
}
You can call this in doInBackground:
runOnUiThread(new Runnable() {
public void run() {
//Your code
}
});
But isn't right... Please read the AsyncTask for more details, or use the onPostExecute to update UI...
I have an android app that I am having trouble with.
Basically the ProgressDialog is not showing at all. I believe this to be a threading issue of some sort but I don't know how to fix it.
I am using ActionBarSherlock with some Fragments. I am also using the new Android DrawerLayout where I have my options on the drawer, which replace a fragment when clicked.
On first load of my app, I want to check the database to see if the inital data has been downloaded. If not, then I go off and begin an AsyncTask to download the data. This SHOULD have a ProgressDialog display during this, but it doesnt.
Can someone see where I am going wrong? Thanks.
MainScreen - The default landing page/fragment when the app opens
public class MainScreen extends SherlockFragment {
public static final String TAG = "MainScreen";
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.activity_main, container, false);
setHasOptionsMenu(false);
ImageView imgLogo = (ImageView) rootView.findViewById(R.id.imgMainScreen);
imgLogo.setOnClickListener(new ButtonHandler(getActivity()));
checkDatabase();
return rootView;
}
private void checkDatabase() {
//Ensure there is data in the database
DBHelper db = new DBHelper(this.getSherlockActivity());
db.checkDatabase();
}
...
}
DBHelper.checkDatabase() - The method that initiates the download
public void checkDatabase() {
if (isEmpty()) {
//Connect to net and download data
NetworkManager nm = new NetworkManager(activity);
if (!nm.downloadData()) {
Toast.makeText(activity, R.string.internetCheck, Toast.LENGTH_SHORT).show();
}
}
}
and finally
NetworkManager.downloadData() - The method that kicks off the AsyncTask:
public boolean downloadData() {
try {
return new HttpConnection(activity).execute().get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
return false;
}
public class HttpConnection extends AsyncTask<Void, Void, Boolean> {
private ProgressDialog progressDialog;
private Activity m_activity;
protected HttpConnection(Activity activity) {
m_activity = activity;
}
#Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(m_activity);
progressDialog.setMessage("Wait ...");
progressDialog.setCancelable(false);
progressDialog.setMax(100);
progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progressDialog.show();
super.onPreExecute();
}
#Override
protected Boolean doInBackground(Void... params) {
String[] types = new String[]{"type1", "type2", "type3", "type4", };
StringBuilder sb = new StringBuilder();
for(String type : types) {
sb = new StringBuilder();
if(DBHelper.TYPE4_TABLE.equals(type)) {
InputStream is = activity.getResources().openRawResource(R.raw.dbdata);
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
try {
sb.append(reader.readLine());
} catch (IOException e) {
Toast.makeText(activity.getApplicationContext(), "Error retriveving data", Toast.LENGTH_SHORT).show();
Log.e(Constants.TAG, "Error reading data");
e.printStackTrace();
}
} else {
sb = fetchURLData(Constants.ALL_URL+type);
}
cleanDataAndStore(sb, type);
}
return true;
}
#Override
protected void onPostExecute(Boolean result){
progressDialog.hide();
}
}
Using the above code, all I get is a white screen as the app tries to load, and sometimes an ANR. When the download is done, the fragment loads. So it works fine except for the missing ProgressDialog.
PS, Notice I'm setting the activity in each constructor.
Thanks.
Remove .get() from return new HttpConnection(activity).execute().get(); You are basically locking your UI thread. Once removed it should work as AsyncTasks are expected to work.
The purpose is to be Asynchronous so boolean downloadData() should have a return type of void. If you need to do something with the data then you should implement an interface "listener" and pass it to the AsyncTask.
Example Listener:
class TaskConnect extends AsyncTask<Void, Void, ConnectionResponse> {
private final AsyncTaskListener mListener;
/**
*
*/
public TaskConnect(AsyncTaskListener listener) {
...
mListener = listener;
}
#Override
protected void onPreExecute() {
if (mListener != null) {
mListener.onPreExecute(mId);
}
}
#Override
protected ConnectionResponse doInBackground(Void... cData) {
...
return responseData;
}
#Override
protected void onPostExecute(ConnectionResponse response) {
if (mListener != null) {
mListener.onComplete(response);
} else {
LOG.w("No AsyncTaskListener!", new Throwable());
}
}
}
public interface AsyncTaskListener {
public abstract void onPreExecute(int id);
public abstract void onComplete(ConnectionResponse response);
}
My issue was not the common issue of others where they were calling get() method after execute() method. My issue was the Context I was passing to my AsyncTask method. I have a settingsActivity and I have a ReadMeActivity that calls the asynctask task. Instead of using the context in which is was being called (ReadMeActivity.this) I used the settingsActivity which prevented it from being seen. Once I switched it and passed it the context in which the activity was being called it worked.
Hope it helps someone else.
Update1
activity:
public Integer _number = 0;
#Override
public void onCreate(Bundle savedInstanceState) {
if (_number >0)
{
Log.d("onSuccessfulExecute", ""+_number);
}
else
{
Log.d("onSuccessfulExecute", "nope empty songs lists");
}
}
public int onSuccessfulExecute(int numberOfSongList) {
_number = numberOfSongList;
if (numberOfSongList >0)
{
Log.d("onSuccessfulExecute", ""+numberOfSongList);
}
else
{
Log.d("onSuccessfulExecute", "nope empty songs lists");
}
return numberOfSongList;
}
end Update1
UPDATE: AsynchTask has its own external class.
How to pass an value from AsyncTask onPostExecute()... to activity
my code does returning value from onPostExecute() and updating on UI but i am looking for a way to set the activity variable (NumberOfSongList) coming from AsynchTask.
AsyncTask class:
#Override
public void onPostExecute(asynctask.Payload payload)
{
AsyncTemplateActivity app = (AsyncTemplateActivity) payload.data[0];
//the below code DOES UPDATE the UI textView control
int answer = ((Integer) payload.result).intValue();
app.taskStatus.setText("Success: answer = "+answer);
//PROBLEM:
//i am trying to populate the value to an variable but does not seems like the way i am doing:
app.NumberOfSongList = payload.answer;
..............
..............
}
Activity:
public Integer NumberOfSongList;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//Several UI Code
new ConnectingTask().execute();
Log.d("onCreate", ""+NumberOfSongList);
}
What about using a setter method? e.g.
private int _number;
public int setNumber(int number) {
_number = number;
}
UPDATE:
Please look at this code. This will do what you're trying to accomplish.
Activity class
public class TestActivity extends Activity {
public int Number;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
Button btnDisplay = (Button) findViewById(R.id.btnDisplay);
btnDisplay.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast toast = Toast.makeText(v.getContext(), "Generated number: " + String.valueOf(Number), Toast.LENGTH_LONG);
toast.show();
}
});
new TestTask(this).execute();
}
}
AsyncTask class
public class TestTask extends AsyncTask<Void, Void, Integer> {
private final Context _context;
private final String TAG = "TestTask";
private final Random _rnd;
public TestTask(Context context){
_context = context;
_rnd = new Random();
}
#Override
protected void onPreExecute() {
//TODO: Do task init.
super.onPreExecute();
}
#Override
protected Integer doInBackground(Void... params) {
//Simulate a long-running procedure.
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
Log.e(TAG, e.getMessage());
}
return _rnd.nextInt();
}
#Override
protected void onPostExecute(Integer result) {
TestActivity test = (TestActivity) _context;
test.Number = result;
super.onPostExecute(result);
}
}
Just a word of caution: Be very careful when attempting to hold a reference to an Activity instance in an AsyncTask - I found this out the hard way :). If the user happens to rotate the device while your background task is still running, your activity will be destroyed and recreated thus invalidating the reference being to the Activity.
Create a listener.
Make a new class file. Called it something like MyAsyncListener and make it look like this:
public interface MyAsyncListener() {
onSuccessfulExecute(int numberOfSongList);
}
Make your activity implement MyAsyncListener, ie,
public class myActivity extends Activity implements MyAsyncListener {
Add the listener to the constructor for your AsyncTask and set it to a global var in the Async class. Then call the listener's method in onPostExecute and pass the data.
public class MyCustomAsync extends AsyncTask<Void,Void,Void> {
MyAsyncListener mal;
public MyCustomAsync(MyAsyncListener listener) {
this.mal = listener;
}
#Override
public void onPostExecute(asynctask.Payload payload) {
\\update UI
mal.onSuccessfulExecute(int numberOfSongList);
}
}
Now, whenever your AsyncTask is done, it will call the method onSuccessfulExecute in your Activity class which should look like:
#Override
public void onSuccessfulExecute(int numberOfSongList) {
\\do whatever
}
Good luck.