android - Do images with AsyncTask download parallel or sequentially? -


i made asynctask load images recyclerview. has method downloadimage() call every time @ viewholder. each image should create new asynctask? can't figure out if download parallel or sequentially. (i can't use libraries, must custom)

private static class downloadimage extends asynctask<string, void, bitmap> {      private imageview mbitmapimage;      downloadimage(imageview imageview) {         mbitmapimage = imageview;     }      @override     protected bitmap doinbackground(string... strings) {         string url = strings[0];         bitmap bitmapimage = null;         inputstream in = null;          try {             in = new url(url).openstream();             bitmapimage = bitmapfactory.decodestream(in);             in.close();         } catch (ioexception e) {             e.printstacktrace();         } {             if (in != null) {                 try {                     in.close();                 } catch (ioexception e) {                     e.printstacktrace();                 }             }         }         return bitmapimage;     }      @override     protected void onpostexecute(bitmap result) {         if (result != null) {             mbitmapimage.setimagebitmap(result);         } else {             mbitmapimage.setimageresource(r.drawable.loading_movie);         }     } }  public static void downloadimage(string imagelocation, imageview imageview) {     new downloadimage(imageview).execute(movie_poster_url_request + imagelocation); }

in adapter call this:

void bindmovie(movie movie) {         mmovie = movie;         mmovietitle.settext(movie.gettitle());         mdescription.settext(movie.getoverview());         downloadimage(movie.getposterpath(), mposter);     }

it depends on version of android system.

but if want sure execute tasks in parallel, use (from support v.4 library): asynctaskcompat.executeparallel(task, params);

in-depth explanation (see accepted answer): running multiple asynctasks @ same time -- not possible?

update:

as stated, asynctaskcompat.executeparallel(task, params); deprecated in api 26, though couldn't find explanation why.

so, docs saying, instead should use asynctask.executeonexecutor(task, params);

to achieve parallel execution:

asynctask.executeonexecutor(asynctask.thread_pool_executor, params);

this method typically used thread_pool_executor allow multiple tasks run in parallel on pool of threads managed asynctask, can use own executor custom behavior.


Comments

Post a Comment

Popular posts from this blog

Is there a better way to structure post methods in Class Based Views -

i'm using class based views in django , never specify url in ajax calls , omit action parameter in form because know these requests go through post method of class based view. notice view - profile page make many requests depending on user updating on page - post method become convoluted , if/else mess example: def post(self, request, *args, **kwargs): # handle user changing available date if request.post.get('availabledate') != none: self.updateavailabledate(request) return jsonresponse({'result':'success'}) if request.post.get('newprojectname') != none: creative_user = creativeuserprofile.objects.get(id = request.user.id) project = project.create_project(creative_user, request.post['newprojectname']) project.save() return jsonresponse({'projectid': project.id }) if request.post.get('projectimage') != none , request.files['file']: proj
Read more

performance - Why is XCHG reg, reg a 3 micro-op instruction on modern Intel architectures? -

i'm doing micro-optimization on performance critical part of code , came across sequence of instructions (in at&t syntax): add %rax, %rbx mov %rdx, %rax mov %rbx, %rdx i thought had use case xchg allow me shave instruction , write: add %rbx, %rax xchg %rax, %rdx however, dimay found agner fog's instruction tables , xchg 3 micro-op instruction 2 cycle latency on sandy bridge, ivy bridge, broadwell, haswell , skylake. 3 whole micro-ops , 2 cycles of latency! 3 micro-ops throws off 4-1-1-1 cadence , 2 cycle latency makes worse original in best case since last 2 instructions in original might execute in parallel. now... cpu might breaking instruction micro-ops equivalent to: mov %rax, %tmp mov %rdx, %rax mov %tmp, %rdx where tmp anonymous internal register , suppose last 2 micro-ops run in parallel latency 2 cycles. given register renaming occurs on these micro-architectures, though, doesn't make sense me done way. why wouldn't register renamer
Read more

jquery - Responsive Navbar with Sub Navbar -

good day, forgive me nav vocabulary not best. if question confusing apologize. i'm working on navigation bar needs centered on page @ 768px , above. items in nav open (or perhaps toggle) subnav lives directly below. these nav should appear centered on page. i have been able work through responsive portion of nav bar, having main items align vertically , sub nav menu of each item roll out below, , gave them indent separation. working well. however, issue not responsive side, behavior @ width greater 768px. happens toggling menu's sub navigation pushes other main items down page below sub nav. here's code: $(document).ready(function () { //stick in fixed 100% height behind navbar don't wrap $('#slide-nav.navbar-inverse').after($('<div class="inverse" id="navbar-height-col"></div>')); $('#slide-nav.navbar-default').after($('<div id="navbar-height-col"></d
Read more