java - Swing ProgressMonitor not working -


i trying learn progressmonitor in java swing. created simple test code -

public class progressmonitortest extends jframe  { private jpanel contentpane; private progressmonitor progressmonitor; private jbutton button; private static progressmonitortest frame; private static boolean isframeready;  public jbutton getbutton() {     return button; }  public progressmonitor getprogressmonitor() {     return progressmonitor; }  /**  * launch application.  */ public static void main(string[] args)  {     eventqueue.invokelater(new runnable()      {         public void run()          {             try              {                 frame = new progressmonitortest();                 frame.setvisible(true);                 isframeready = true;             }              catch (exception e)              {                 e.printstacktrace();             }         }     });      while(!isframeready)     {         //     }      frame.getbutton().addactionlistener(new actionlistener()      {            @override         public void actionperformed(actionevent e)          {             try             {                 for(int i=0;i<=10;i++)                 {                     final int percent = i;                     swingutilities.invokeandwait(new runnable()                      {                            @override                         public void run()                         {                             frame.getprogressmonitor().setprogress(percent * 10);                             frame.getprogressmonitor().setnote("completed " + percent*10 + "%.");                         }                     });                     try                     {                         thread.sleep(1000);                     }                     catch(exception ee)                     {                         //                     }                                            }             }             catch(exception es)             {                 //             }         }                }); }  /**  * create frame.  */ public progressmonitortest()  {     isframeready = false;      setdefaultcloseoperation(jframe.exit_on_close);     setbounds(100, 100, 450, 300);     settitle("progress monitor");      contentpane = new jpanel();     contentpane.setborder(new emptyborder(5, 5, 5, 5));     contentpane.setlayout(new borderlayout(0, 0));      progressmonitor = new progressmonitor(frame, "update in progress...", "", 0, 10);     button = new jbutton("click here");     contentpane.add(button);      setcontentpane(contentpane); }

}

a few questions regarding this-

  1. if remove isframeready check, program says nullpointerexception @ line assign button's action listener.

  2. if keep above check, clicking on button nothing.

  3. keeping above check , debugging this, let wait time before gets line action listener. in case, works quits saying can't call invokeandwait event handling thread.

what missing in ? can explain how work.

if remove isframeready check, program says nullpointerexception @ line assign button's action listener.

your use of isframeready ensures have created frame successfully. inside main, posted request event dispatch thread(edt) using call eventqueue.invokelater(new runnable(){}): removing check isframeready, going call frame.getbutton() in main thread frame have not been yet created frame = new progressmonitortest(); in edt , nullpointerexception occurs.

if keep above check, clicking on button nothing.

you should understand now, above check nothing button click. button not doing because gui got freezed violating swing's single threading rule. put incrementing for loop of actionperformed method inside thread following code fragement shows , execute there. see works fine.

 new thread(){     public void run()     {        for(int i=0; i<10; i++)         {            //whatever doing.         }     }    }.start();

keeping above check , debugging this, let wait time before gets line action listener. in case, works quits saying can't call invokeandwait event handling thread.

swingutitlies.invokeandwait() blocks current thread , waits until edt done executing task given it. actionperformed() function running inside edt, calling swingutitlies.invokeandwait() current thread:edt block current thread:edt should not allowed. don't use invokeandwait case. should call swingutilities.invokelater() instead.

however don't think until understand swing threading model. read javadoc , internet resource. have book filthy rich clients , try example book offered: have greater knowledge in graphical effects other resource can provide.


Comments

Post a Comment

Popular posts from this blog

c++ - CryptStringToBinary API behavior -

i seeing strange behavior cryptstringtobinary cryptography api. please see below code (config: x64 debug): #include "stdafx.h" #include <windows.h> #include <strsafe.h> #include <iostream> #include <exception> void main() { dword dwskip; dword dwflags; dword dwdatalen; //lpcwstr pszinput = l"jaaaaaecaaadzgaaakqaagdnnl1l56bwgfjdgr3rpxtqqqn6daw3usv2emkjym4t"; //this works fine lpcwstr pszinput = l"mytest"; //doesnt work, api returns false,error code 0x0000000d // determine size of byte array , allocate memory. if(! cryptstringtobinary( pszinput, _tcslen( pszinput ) + 1, crypt_string_base64, null, &dwdatalen, &dwskip, &dwflags ) ) { dword dw = getlasterror(); //0x0000000d: data invalid throw std::exception( "error computing byte length." ); } byte *pbytebyte = null; try { ...
Read more

c++ - Correct method for redrawing a layered window -

i have window created ws_ex_layered window style. drawing onto memory bitmap using gdi+, , using updatelayeredwindow update graphical content of layered window. intend use window main window of application, require redraw frequently. seeing layered windows not receive wm_paint windows message [?] , need come appropriate method re-drawing window. optimisation not essential , it's nice have cake , eat too. therefore, in search of "correct" method use. here thoughts far: i guess it's idea render onto off-screen bitmap before bitblt ing or similar. 60 frames rendered per second should (more than?) enough (but how compare other applications' frame rates?). possible solutions: use settimer send wm_timer message on regular basis. useful because through specifying time-out value, can achieve desired frames per second, without requirement measure duration "frame" takes rendered. would cause input or other lags due frequency , speed of m...
Read more

java.util.scanner - How to read and add only numbers to array from a text file -

i'm learning java , have question regarding reading file want read numbers file contains strings well. here example of file: 66.56 "3 java 3-43 5-42 2.1 1 and here coding: public class test { public static void main (string [] args){ if (0 < args.length) { file x = new file(args[0]); try{ scanner in = new scanner( new fileinputstream(x)); arraylist<double> test = new arraylist<>(); while(in.hasnext()){ if(in.hasnextdouble()){ double f=in.nextdouble(); test.add(f);} else {in.next();} } catch(ioexception e) { system.err.println("exception during reading: " + e); } } my problem add 66.56,2.1 , 1 doesn't add 3 after "3 or ignores 3-43 , 5-42 can tell me how skip strings , add doubles here? thanks all said 3 ie; "3, 3-43 , 4-42 strings either u read string , split , check number @ " , - or put in space between characters , integers. jvm after compilation tre...
Read more