swing - Problems with loops in GUI (java) -


i'm pretty new java, , started writing dumb little program gui test. it's supposed have 12 buttons, set them white, continuously make 3 random buttons black, set buttons white again, wait 1 second , repeat. problem is, can't seem make repeat. every time try put while or loop around section of code makes random buttons black, won't run. doesn't give errors, , process run, no window appears. code class (minus import statements):

public class testingness extends jframe {  jbutton one, two, three, four, five, six, seven, eight, nine, ten, eleven,         twelve; jpanel panel;  testingness(string title) {      super(title);     this.init();     this.setsize(800, 800);     this.setlocationrelativeto(null);     this.setvisible(true); }  void init() {     panel = new jpanel();     panel.setlayout(new gridlayout(3, 4));     1 = new jbutton();     one.setbackground(color.white);     2 = new jbutton();     two.setbackground(color.white);     3 = new jbutton();     three.setbackground(color.white);     4 = new jbutton();     four.setbackground(color.white);     5 = new jbutton();     five.setbackground(color.white);     6 = new jbutton();     six.setbackground(color.white);     7 = new jbutton();     seven.setbackground(color.white);     8 = new jbutton();     eight.setbackground(color.white);     9 = new jbutton();     nine.setbackground(color.white);     ten = new jbutton();     ten.setbackground(color.white);     eleven = new jbutton();     eleven.setbackground(color.white);     twelve = new jbutton();     twelve.setbackground(color.white);      panel.add(one);     panel.add(two);     panel.add(three);     panel.add(four);     panel.add(five);     panel.add(six);     panel.add(seven);     panel.add(eight);     panel.add(nine);     panel.add(ten);     panel.add(eleven);     panel.add(twelve);      this.add(panel);     while (true) {         randomness();         try {             thread.sleep(1000);         } catch (interruptedexception e) {             // todo auto-generated catch block             e.printstacktrace();         }     } }  public void randomness() {      (int timesdone = 0; timesdone < 4; timesdone++) {         panel.update(panel.getgraphics());         random r = new random();         int rand = r.nextint(12);          if (rand == 0) {             one.setbackground(color.black);         } else if (rand == 1) {             two.setbackground(color.black);         } else if (rand == 2) {             three.setbackground(color.black);         } else if (rand == 3) {             four.setbackground(color.black);         } else if (rand == 4) {             five.setbackground(color.black);         } else if (rand == 5) {             six.setbackground(color.black);         } else if (rand == 6) {             seven.setbackground(color.black);         } else if (rand == 7) {             eight.setbackground(color.black);         } else if (rand == 8) {             nine.setbackground(color.black);         } else if (rand == 9) {             ten.setbackground(color.black);         } else if (rand == 10) {             eleven.setbackground(color.black);         } else if (rand == 11) {             twelve.setbackground(color.black);         }         one.setbackground(color.white);         two.setbackground(color.white);         three.setbackground(color.white);         four.setbackground(color.white);         five.setbackground(color.white);         six.setbackground(color.white);         seven.setbackground(color.white);         eight.setbackground(color.white);         nine.setbackground(color.white);         ten.setbackground(color.white);         eleven.setbackground(color.white);         twelve.setbackground(color.white);      }   }  }

what doing wrong here?

as germann arlington pointed out, gui thread never being allowed run because constructor never returns. however, better means of getting performed on regular basis on gui thread (which need change attributes of gui components) use timer (http://docs.oracle.com/javase/7/docs/api/javax/swing/timer.html). e.g.:

int delay = 1000; //milliseconds actionlistener taskperformer = new actionlistener() {     public void actionperformed(actionevent evt) {         randomness();     } }; new timer(delay, taskperformer).start();

-

Popular posts from this blog

php - How should I create my API for mobile applications (Needs Authentication) -

background so i've been researching quite bit past week api's , have been reading concepts , programming one. currently have website programmed in php using popular framework called laravel. website has user database , users able log dashboard on website, works want website side. now next project of business i'm focusing on creating mobile applications (ios & andriod).what need these mobile applications being able login through application ui (not being redirected site callback url) able view , manage dashboard. the method of authentication , authorization want use application go like client asks user login through ui user enters credentials client sends request login api the api checks if credentials correct api creates token stored in token database linked user id api returns 200 ok json response or this { "token" : "ols25usjiay81hdy81", "expiry" : 3/06/2016 14:00} client remembers token , expiry whenever user/c...
Read more

python 3.x - PyQt5 - Signal : pyqtSignal no method connect -

following example in doc found on sourceforge faced error. from pyqt5.qtcore import pyqtsignal, pyqtslot def setsignal(): signal = pyqtsignal() signal.connect(self.myaction) @qtcore.pyqtslot() def myaction(): print("signal triggered") results in attributeerror: 'pyqt5.qtcore.pyqtsignal' object has no attribute 'connect' as mentioned in docs linked, signal needs defined on class level: class foo(qobject): signal = pyqtsignal() def connectsignal(): self.signal.connect(self.myaction) @qtcore.pyqtslot() def myaction(): print("signal triggered")
Read more

5 Reasons to Blog Anonymously (and 5 Reasons Not To)

Image
This guest post is by Phil (not his real name) of somehighschoolblog . It used to be impossible to run a business anonymously. Sure, some authors could pull it off, but if you worked at an office, what were you supposed to do? Go to work with a bag over your head? But today anyone can accomplish this, because anyone can author a blog (and you thought I was going to tell you to work with a mask on, or something). Copyright Ovidiu Iordachi - Fotolia.com Depending on your motives, you may or may not have considered blogging anonymously. You probably didn’t contemplate blogging anonymously if: • your only motivation is to become “famous” • your blog connects to another part of your life • you are blogging to build more connections with your friends or boss. You should consider blogging anonymously if: • you’re planning on touching on a sensitive or taboo subject • you don’t want to be identified with your blog • you are worried about negative real-world consequences that could arise from y...
Read more