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
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
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
Why can't you just let webview evaluate the JavaScript?
On 18 January 2012 15:18, tatebn brandonnt...@gmail.com wrote:
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
WebView doesn't evaluate the JavaScript synchronously. I need an
immediate return not a call to a separate interface method. The only
method I've found of anyone evaluating javascript synchronously is
using this semaphore method, but I can't get the javascript to
continue evaluating when the
We use a countdown latch instead:
private CountDownLatch latch = null;
public void run(String javaScript, int waitInMilliSecs) {
latch = new CountDownLatch(1);
runJS(javaScript); // this method just runs the given javascript in the
WebView.
try {
latch.await(waitInMilliSecs,
We use a countdown latch instead:
String returnValue;
private CountDownLatch latch = null;
public String run(String javaScript, int waitInMilliSecs) {
latch = new CountDownLatch(1);
runJS(javaScript); // this method just runs the given javascript in the
WebView.
try {
I'm getting the same issue using the CountDownLatch. The WebView
can't load the url because of the lock.
On Jan 18, 11:01 am, Streets Of Boston flyingdutc...@gmail.com
wrote:
We use a countdown latch instead:
String returnValue;
private CountDownLatch latch = null;
public String
Why does your JS has to be synchronous?
Simply within JS make body of your page a throbber and only swap it
back to its actual content as a last statement in the JS function that
you want to process.
On 18 January 2012 16:24, tatebn brandonnt...@gmail.com wrote:
I'm getting the same issue
... we use it successfully all over the place.
For some reason, it seems that the stack-frame of your call to loadUrl in
your code needs to finish before the javascript in 'code' is actually
executed. The call to 'loadUrl' should cause the javascript to be executed
on a separate thread
I need to put up a context menu in the app when the user selects text
in the WebView. The options in that context menu depend on yes or no
answers I pull from javascript. The content is local content that is
set up to deliver these answers.
if(webView.needsOption1())
// Add option1 to
I've tried executing the javascript in an async task, which I thought
would fix any threading issues. But I get the same issue. How do you
have your threads specified when you run yours? Are you running this
from a WebView subclass or from a separate class for you javascript
interface? I've
It's from a separate class (runJS does something like
mWebView.loadUrl(javaScriptUrl);)
In my sample code, the *run *and *runJS *are usually executed on the main
UI thread (that's why there the *await *call has a (short) timeout).
The WebView's JavaScript execution's callback to Java (setValue
You can bind Java code from within your JavaScript by calling
*WebView.addJavascriptInterface()*. In other words you could call one
method within Java object of your choosing, when user selects A in UI
or different method of different object, when user interacts with UI
differently.
JavaDocs are
My getJSValue() is run on the main thread as well.
As far as the latch.await goes,
If I run webView.loadUrl() in an asyncTask I get the full time out (10
seconds for testing).
If I just run webView.loadUrl() in the current task, there is no time
out. The latch.await call instantly comes back,
It should read that you can bind your Java code so it is accessible
from JavaScript. Obviously the biding is defined within your Java
code, and JavaScript assumes existence of said binding.
Reading through the example should clarify...
On 18 January 2012 17:41, Daniel Drozdzewski
Nevermind that. Misread the log. The latch.await times out every
time. But the javascript is not evaluated until after the timeout.
On Jan 18, 12:21 pm, Streets Of Boston flyingdutc...@gmail.com
wrote:
It's from a separate class (runJS does something like
mWebView.loadUrl(javaScriptUrl);)
Thanks, but I have the javascript to java binding working. My issue
is that I need to wait and return the value set via that binding from
javascript. But it seems that the loadUrl() method in the web view
isn't using it's own thread. So any waiting I'm doing stops the
javascript from executing.
Very odd.
The call to loadUrl should just post a message with the Url on the
WebViewCore which, in its turn, will run this url (javascript) on its own
thread-pool.
I would examine your JavaScript as well. Maybe it does something that needs
to be run on the same thread on which you call
The javascript is actually generated in the getJSValue method. For
this test I'm using 2 + 2 as my expression. So I don't think the
actual js is the issue.
How do I tell which thread which method call is happening in?
On Jan 18, 1:20 pm, Streets Of Boston flyingdutc...@gmail.com wrote:
Very
Nevermind. Looks like loadUrl() is being loaded in the main thread.
And setValue() is being called in the WebViewCoreThread.
On Jan 18, 2:12 pm, tatebn brandonnt...@gmail.com wrote:
The javascript is actually generated in the getJSValue method. For
this test I'm using 2 + 2 as my expression.
That looks good.
Now enable the latch again (call await) and run your app. When your app
hangs, debug it: Press 'pause' on your app that will suspend all your
threads. Then open/expand the threads so you see each thread's stack-trace.
One should be at the 'await' call. Look at other threads
Ok. I got it. And I feel a little bit stupid.
I have multiple url schemes I'm using within the app to do things like
send analytics, etc.
One of those schemes is finishedloading://, which tells me that the
page is ready for me to inject javascript.
In my shouldOverrideMethod,
if
Ah... we've all been there. Any programmer/developer can relate to the
situation that one missing silly semicolon messing up your code can be
overlooked for a long time, followed by a big
forehead-slapping.
Anywhose, it's quite amazing what info you can get by just examining your
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