I need the semaphore to hold there so that the return doesn't happen
until the value is sent back from javascript. How do I get the web
view to continue evaluating the javascript in the background?
On Jan 18, 10:05 am, Daniel Drozdzewski <daniel.drozdzew...@gmail.com>
wrote:
> Your semaphore allows ZERO passes through, in which case you have to
> release first.
>
> Either change the parameter to Semaphore constructor or release before
> calling Semaphore.acquire()
>
> Daniel
>
> On 18 January 2012 15:00, tatebn <brandonnt...@gmail.com> wrote:
>
>
>
>
>
>
>
>
>
> > By the way, this code is located in a subclassed WebView.
>
> > On Jan 18, 9:53 am, tatebn <brandonnt...@gmail.com> wrote:
> >> I'm trying to evaluate javascript with a semaphore lock. I need to
> >> query some web content about which context menus to show and need it
> >> to be synchronous. When I try to acquire the semaphore the thread
> >> locks without the javascript being evaluated and my javascript
> >> interface method being called.
>
> >> Here's my code.
>
> >> private Semaphore returnSemaphore = new Semaphore(0);
> >> private String returnValue;
>
> >> public String getJSValue(String expression)
> >> {
> >> String code =
> >> "javascript:_JSEval.setValue((function(){try{return "
> >> + expression
> >> + "+\"\";}catch(js_eval_err){return '';}})());";
> >> //String code = "javascript: alert('here');";
> >> Log.d(TAG, "eval: " + code);
>
> >> this.loadUrl(code);
>
> >> try {
> >> Log.d(TAG, "eval: about to acquire semaphore, " +
> >> returnSemaphore.availablePermits());
>
> >> returnSemaphore.acquire();
>
> >> Log.d(TAG, "past semaphore acquire");
>
> >> return returnValue;
> >> } catch (InterruptedException e) {
> >> Log.e(TAG, "eval: Interrupted", e);
> >> }
> >> return null;
>
> >> }
>
> >> @SuppressWarnings("unused")
> >> private class JSEval
> >> {
> >> public void setValue(String value)
> >> {
> >> Log.i(TAG, "eval: in set value");
> >> //if (value != null) {
> >> returnValue = value;
> >> //}
> >> returnSemaphore.release();
> >> }
> >> }
>
> >> If I remove the semaphore acquire call, I get a result in setValue, so
> >> I know the interface is working.
>
> > --
> > You received this message because you are subscribed to the Google
> > Groups "Android Developers" group.
> > To post to this group, send email to android-developers@googlegroups.com
> > To unsubscribe from this group, send email to
> > android-developers+unsubscr...@googlegroups.com
> > For more options, visit this group at
> >http://groups.google.com/group/android-developers?hl=en
>
> --
> Daniel Drozdzewski
--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
