On Apr 16, 2012, at 7:04 PM, Paul Johnson wrote:
> JNIEnv.Get*ID requires the type of the variable to be IntPtr, but then
> requires IntPtr kls, string name, string signature for the parameters.
> Unfortunately, the documentation on the API area gives the "documentation to
> be added" line for kls which isn't much help.
As per the API Design document [0], you can (normally) use the similarly named
JNI function documentation:
http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/functions.html
In particular, for e.g. GetMethodID(), you want a Class reference, the name of
the method, and the method signature:
http://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/functions.html#wp16656
The Binding Android Types documentation may also be helpful:
http://docs.xamarin.com/android/advanced_topics/Binding_Android_Types#_Instance_Methods
http://docs.xamarin.com/android/advanced_topics/Binding_Android_Types#JNI_Type_Signatures
> private bool prepareModal()
> {
using (var MessageQueue_Class =
Java.Lang.Class.FromType(typeof(Android.OS.MessageQueue)))
using (var Message_Class =
Java.Lang.Class.FromType(typeof(Android.OS.Message))) {
mMsgQueueNextMethod =
JNIEnv.GetMethodID(MessageQueue_Class.Handle,
"next", "()Landroid/os/Message;");
mMsgTargetField = JNIEnv.GetFieldID(Message_Class.Handle,
"target", "Landroid/os/Handler;");
return true;
}
> private void doModal()
> {
> mQuitModal = false;
>
> // get message queue associated with main UI thread
> MessageQueue queue = Looper.MyQueue();
> while (!mQuitModal)
> {
> // call queue.next(), might block
> Message msg = null;
> try
> {
> // invoke not available
> msg = (Message)mMsgQueueNextMethod.invoke(queue, new
> Object[] { });
IntPtr _msg = JNIEnv.CallObjectMethod(queue.Handle,
mMsgQueueNextMethod);
if (_msg == IntPtr.Zero)
return;
using (msg = Java.Lang.Object.GetObject<Android.OS.Message>(_msg,
JniHandleOwnership.TransferLocalRef)) {
IntPtr _target = JNIEnv.GetObjectField(msg.Handle,
mMsgTargetField);
if (_target == IntPtr.Zero) {
mQuitModal = true;
return;
}
using (var target =
Java.Lang.Object.GetObject<Android.OS.Handler>(_target,
JniHandleOwnership.TransferLocalRef)) {
target.DispatchMessage(msg);
msg.Recycle();
}
}
- Jon
[0]
http://docs.xamarin.com/android/advanced_topics/api_design#Java_Native_Interface_Support
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