java - Update JLabel repeatedly with results of long running task -

i'm writing program pings server. wrote code check once , put ping in jlabel , put in method called setping().

here code

private void formwindowopened(java.awt.event.windowevent evt) {                                       setping(); }            

that worked did once, did:

private void formwindowopened(java.awt.event.windowevent evt) {                                   for(;;){     setping();     } }            

but doesn't work first time.

i didnt put setping method because long here is:

public string setping(){ runtime runtime = runtime.getruntime();  try{     process process = runtime.exec("ping lol.garena.com"); inputstream = process.getinputstream();  inputstreamreader isr = new inputstreamreader(is);  bufferedreader br = new bufferedreader(isr);  string line;  while ((line = br.readline()) != null) {     int = 0;       = line.indexof("average");     if(i > 0){       string finalping = "";     line.tochararray();     try     {         finalping = "";         for(int x = i; x < + 17; x++)         {             finalping = finalping + (line.charat(x));         }     }catch(indexoutofboundsexception e)     {         try         {             finalping = "";             for(int x = i; x < + 16; x++)             {                 finalping = finalping + (line.charat(x));             }         }catch(indexoutofboundsexception f)         {             try             {                 finalping = "";                 for(int x = i; x < + 15; x++)                 {                     finalping = finalping + (line.charat(x));                 }             }catch(indexoutofboundsexception g){}         }     }     string final1ping = finalping.replaceall("[^0-9]", "");     return final1ping;     } }  }catch(ioexception e){ } return ""; } 

update in case important, im using netbeans. created form , put code in formwindowopened evt instead of calling in main:

private void formwindowopened(java.awt.event.windowevent evt) {                                        actionlistener timerlistener = new actionlistener() {          @override         public void actionperformed(actionevent e) {             new pingworker().execute();         }     };     timer timer = new timer(1000, timerlistener);           timer.start();         jlabel1.settext(label.gettext());         timer.stop();  // todo add handling code here: }                                   class pingworker extends swingworker {      int time;      @override     protected object doinbackground() throws exception {         time = pingtime("lol.garena.com");         return new integer(time);     }      @override     protected void done() {         label.settext("" + time);     } };  public jcomponent getui() {     return label; }  public static int pingtime(string hostnameorip) {     socket socket = null;     long start = system.currenttimemillis();     try {         socket = new socket(hostnameorip, 80);     } catch (ioexception ex) {         ex.printstacktrace();     } {         if (socket != null) {             try {                 socket.close();             } catch (ioexception e) {             }         }     }     long end = system.currenttimemillis();     return (int) (end - start); } 

use swing timer repeating tasks & swingworker long running tasks. e.g. of both below - uses timer repeatedly perform 'long running' task (a ping) in swingworker.

see concurrency in swing more details on event dispatch thread , doing long running or repeating tasks in gui.

this code combines long running task ('pinging' server) using swingworker invoked repeating task (updating jlabel repeatedly times) using swing based timer.

import java.awt.event.*; import javax.swing.*; import java.net.socket;  public class labelupdateusingtimer {      static string hostnameorip = "stackoverflow.com";     int delay = 5000;     jlabel label = new jlabel("0000");      labelupdateusingtimer() {         label.setfont(label.getfont().derivefont(120f));          actionlistener timerlistener = new actionlistener() {             @override             public void actionperformed(actionevent e) {                 new pingworker().execute();             }         };         timer timer = new timer(delay, timerlistener);          timer.start();         joptionpane.showmessagedialog(                 null, label, hostnameorip, joptionpane.information_message);         timer.stop();     }      class pingworker extends swingworker {          int time;          @override         protected object doinbackground() throws exception {             time = pingtime();             return new integer(time);         }          @override         protected void done() {             label.settext("" + time);         }     };      public static int pingtime() {         socket socket = null;         long start = system.currenttimemillis();         try {             socket = new socket(hostnameorip, 80);         } catch (exception wetried) {         } {             if (socket != null) {                 try {                     socket.close();                 } catch (exception wetried) {}             }         }         long end = system.currenttimemillis();         return (int) (end - start);     }      public static void main(string[] args) {         runnable r = new runnable() {             @override             public void run() {                 new labelupdateusingtimer();             }         };         swingutilities.invokelater(r);     } }