How to download a file after clicking a button (Android Studio) -

i created activity in app. wanted user download .pdf file when he/she wants view guidelines. wanted implement on button. idea how properly?

heres code below:

public class exhibitor_registration_activity extends appcompatactivity  {      button buttondownload;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_exhibitor_registration_);          this.settitle("buyer registration");          toolbar mytoolbar = (toolbar) findviewbyid(r.id.my_toolbar);         setsupportactionbar(mytoolbar);         getsupportactionbar().setdisplayhomeasupenabled(true);         mytoolbar.setnavigationicon(r.drawable.ic_arrow_back_white_24dp);          final button buttondownload = (button) findviewbyid(r.id.buttondownload);          buttondownload.setonclicklistener(new view.onclicklistener(){              @override             public void onclick(view view) {                 try {                     //this file want download remote server                     string path ="http://www.manilafame.com/website-assets/downloads/exhibitor-application-kit/local/201704/1-summary-of-participation-details-april-2017_mn_002.pdfp";                     //this name of local file create                     string targetfilename = null;                     boolean eof = false;                     url u = new url(path);                     httpurlconnection c = (httpurlconnection) u.openconnection();                     c.setrequestmethod("get");                     c.setdooutput(true);                     c.connect();                     fileoutputstream f = new fileoutputstream(new file("c:\\junk\\"+targetfilename));                     inputstream in = c.getinputstream();                     byte[] buffer = new byte[1024];                     int len1 = 0;                     while ( (len1 = in.read(buffer)) > 0 ) {                         f.write(buffer,0, len1);                     }                     f.close();                 } catch (malformedurlexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 } catch (protocolexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 } catch (filenotfoundexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 } catch (ioexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 }             }         });     } } 

i got source code here , here.

if want resumable, speed of download ... follow steps

create class downloadmanager.java

public class downloadmanager extends asynctask<string,string,string>{ string downloadlink,filedestination; public static final int on_init=100,on_error=102,on_prograss=103,on_completed=104,status_downloaded=1500,status_not_yet=1501; private onupdatelistener onupdatelistener; private string downloadedpath=""; private long downloaded=0; private file file; private string returndata=null; private file cachedownloadfile; public downloadmanager(string downloadlink,string filedestinationpath){     this.downloadlink=downloadlink;     this.filedestination=filedestinationpath;     file=new file(filedestination, tools.getfilename(downloadlink));     cachedownloadfile=new file(appcostants.chache_path+tools.getfilename(downloadlink));     try {         if(cachedownloadfile.isfile())             downloaded=tools.getfilesize(cachedownloadfile);         else             downloaded=0;         log.d("file_download_tag_p",downloaded+" <- "+cachedownloadfile.getabsolutepath());     } catch (ioexception e) {         e.printstacktrace();     }     fireonupdate(on_init,"init ...");  } @override protected string doinbackground(string... params) {     try {         file dir=new file(filedestination);         file chachedir=new file(appcostants.chache_path);         if(!chachedir.isdirectory())             chachedir.mkdirs();         if(!dir.isdirectory()){             dir.mkdirs();         }          if(file.exists()) {             log.d("file_download_tag","file exist return complete");             return "completed";//file exist         }         if(!cachedownloadfile.exists()){             cachedownloadfile.createnewfile();         }         log.d("file_download_tag","link "+downloadlink);         url url=new url(downloadlink);         httpurlconnection urlconnection= (httpurlconnection) url.openconnection();         if(downloaded>0)             urlconnection.setrequestproperty("range","byte="+downloaded);         urlconnection.connect();         int status = urlconnection.getresponsecode();         inputstream inputstream=urlconnection.getinputstream();         int totalsize=urlconnection.getcontentlength();         if(totalsize<=downloaded){             returndata= "completed";             publishprogress("file checked "+tools.getfilename(file.getabsolutepath()));             return returndata;         }         this.downloadedpath=cachedownloadfile.getabsolutepath();         byte[] buffer=new byte[1024];         int bufferlength=0;         fileoutputstream fileoutput=new fileoutputstream(cachedownloadfile);         long d=0;         long starttime=system.currenttimemillis();         while ((bufferlength=inputstream.read(buffer))>0){             fileoutput.write(buffer,0,bufferlength);             downloaded+=bufferlength;             d+=bufferlength;             //string l=" "+tools.getfilename(file.getabsolutepath())+" ( "+tools.convertmemory(downloaded)+" / "+tools.convertmemory(totalsize)+" )";             string l="  "+tools.convertmemory(downloaded)+" / "+tools.convertmemory(totalsize)+" ( "+getdownloadspeed(starttime,d)+" )";             publishprogress(l);             if(downloaded>=totalsize){                 break;             }         }         log.d("file_download_tag","dwonloaded "+downloadedpath+" ("+cachedownloadfile.length()+")");         fileoutput.close();         if(tools.filecopy(file,cachedownloadfile)){             log.d("file_download_tag","file copied, delete cache");             cachedownloadfile.delete();         }         returndata="completed";     } catch (malformedurlexception e) {         returndata=null;         e.printstacktrace();         publishprogress(e.tostring());         log.d("###################",e+"");      } catch (ioexception e) {         returndata=null;         e.printstacktrace();         publishprogress(e.tostring());     }      return returndata; }  @override protected void onprogressupdate(string... values) {     super.onprogressupdate(values);     fireonupdate(on_prograss,values[0]); }  @override protected void onpostexecute(string s) {     super.onpostexecute(s);     if(s!=null){         fireonupdate(on_completed,downloadedpath);     }else{         fireonupdate(on_error,"download failed");     } }  public interface onupdatelistener{     void onupdate(int code,string message); } public void setonupdatelistener(onupdatelistener onupdatelistener){     this.onupdatelistener=onupdatelistener; } private void fireonupdate(int code,string message){     if(onupdatelistener!=null)         onupdatelistener.onupdate(code,message); }  private string getdownloadspeed(long starttime,float totaldownloaded) {     long elapsedtime = system.currenttimemillis() - starttime;     //byte :     float speed=1000f * totaldownloaded / elapsedtime;     return convert(speed); } private string convert(float value){     long kb=1024             ,mb=kb*1024             ,gb=mb*1024;      if(value<kb){         string speed=(value+"");         speed=speed.substring(0,speed.indexof('.')+2);         return speed+" b/s";     }else if(value<mb){         value=value/kb;         string speed=(value+"");         speed=speed.substring(0,speed.indexof('.'));         return (speed)+" kb/s";     }else if(value<gb){         value=(value/mb);         string speed=(value+"");         speed=speed.substring(0,speed.indexof('.'));         return speed+" mb/s";     }     return ""; } } 

2. use code in onclick() downloadmanager downloadmanager = new downloadmanager(url,filepath);

3. set event

   downloadmanager.setonupdatelistener(new downloadmanager.onupdatelistener() { @override public void onupdate(int code, string message) { if (code == downloadmanager.on_completed) {                  }                 if(downloadmanager.on_prograss==code){}              }         }); 

4. start download

   downloadmanager.execute(); 

5. lib setup

   compile "commons-io:commons-io:+" 

6. tools.java

   public static long getfilesize(file file) throws ioexception { fileoutputstream fileoutputstream=new fileoutputstream(file); fileoutputstream.close(); return file.length(); } public static boolean filecopy(file dest,file source){ try {     fileutils.copyfile(source,dest);     return true; } catch (ioexception e) {     e.printstacktrace();     return false; } }