使用延迟打开浏览器的多个链接

Question

I did this program that opens multiple link with default browser:

ArrayList<String> linkList = new ArrayList<>();
for (int i = 0; i < linkList.size(); i++) {
  ClassRunnable_OpenLink obj = new ClassRunnable_OpenLink ( linkList.get(i) );
  Thread thread = new Thread(obj);
  thread.start();
}
 private class ClassRunnable_OpenLink implements Runnable {
      private URL link;
      private String string;

         public ClassRunnable_OpenLink (String string) {
             this.string = string;
         }

         private void OpenWithBrowser () {
          try {

              link = new URL ( string );
              edu.stanford.ejalbert.BrowserLauncher launcher = null;
          try {
        launcher = new BrowserLauncher(null);
          } catch (    BrowserLaunchingInitializingException | UnsupportedOperatingSystemException ex) { }
          launcher.openURLinBrowser( link );

          } catch (  MalformedURLException ex | IOException | URISyntaxException ex) {  }
        }

         @Override
         public void run() {  
            OpenWithBrowser( );
         }
  }

This works great only if browser (say it's firefox) is already opened, but if it's not, my program only opens the first link and then I have a firefox message that tells me the the browser is still running so I need to close it first. Same thing with chromium.

So I thought, if I had a way to check when the browser is closed I could use ProcessBuilder to open new firefox process, but I don't know if it's the best way to do this. Besides my java program allows user to select default browser so it could be complicated to use ProcessBuilder in that case.

So do you a have any idea to solve my problem? Maybe I could set a delay between each Thread in this way the system has the time to execute browser process first time, then opening first link and after the browser is running, opening other links, but how about the delay time in seconds? I'm not able to know the time that browser needs to open so it's not a good idea.

I hope you can help me. Thanks

Answer 1

A workaround to this (without knowing your exact expectations), could be to do the following:

• After first URL open, you could build a delay of for example 10 seconds.
• Then in any consecutive URL openings, you can assume that the browser is now surely open, and start opening the next URL's fast after each other.

One note though: Always add some delay to opening URL's (not sure if your framework already does this), because else the browser might crash from the number of URL openings.

UPDATE: You say that Thread.sleep() causes your program to block, this should never happen.

You should always seperate long-during actions from the rest of your program (The (Graphical) User Interface).

So it would be better to write your 'URL opener facility' in another thread.
You can read more about that here: http://docs.oracle.com/javase/tutorial/essential/concurrency/

Answer 2

Since java 6 you don't have to use 3rd party implementations to open a webpage with the standard browser. Try

java.awt.Desktop.getDesktop().browse(uri);

Since this maps to the underlying OS functions chances are high multiple calls will work as expected.