Passing Activity Context to Handler(fragment) for Toast - android-fragments

I'm trying to use a Toast message in a handler fragment class but I can't access the main class' context. The handler is in the same class as the main activity, PlayFrets(which is also the UI thread).I've read through the plethora of questions on this topic on stackoverflow, but almost every solution involves passing getActivity() or getActivity().getApplicationContext() into the context field of Toast. When I try this I get errors
Here is the relevant code:
public class PlayFrets extends Activity {
.
.
.
static Handler mHandler = new Handler(Looper.getMainLooper()){
public void handleMessage(final Message msg){
if(msg.obj != null){
runOnUiThread(new Runnable() {
public void run() {
//error happens here on Toast message
Toast.makeText(getActivity(), "Background Thread sent "+ msg.what + " bytes: " + msg.obj,Toast.LENGTH_SHORT).show();
}
});
}
else{
}
}
};
}
These are my attempts at passing the context and the errors each variation generates.
Toast.makeText(PlayFrets.this.getActivity()...)
^^^The method getActivity() is undefined for the type PlayFrets
Toast.makeText(PlayFrets.this...)
^^^No enclosing instance of the type PlayFrets is accessible in scope
Toast.makeText(getActivity().getApplicationContext()...)
^^^The method getActivity() is undefined for the type new Runnable(){}
What is the proper way to pass the main activity's context into the handler fragement for use in a Toast message?

Activity is a context itself. Instead of all things you try you should
not create static handler - that's why your attempt to pass PlayFrets.this fails
pass PlayFrets.this as context
no need to call runOnUiThread() because handler handles messages on UI thread in presented case
Your handler code should look like this:
Handler mHandler = new Handler() {
public void handleMessage(final Message msg){
if(msg.obj != null){
Toast.makeText(PlayFrets.this, "Background Thread sent "+ msg.what + " bytes: " + msg.obj,Toast.LENGTH_SHORT).show();
}
else{
}
}
};

Related

Flutter and external JAR Library: android.os.NetworkOnMainThreadException

Im trying to use olingo with Flutter on Android. I set up my channel and I can call the library but I keep getting this message:
E/AndroidRuntime(28391): FATAL EXCEPTION: main
E/AndroidRuntime(28391): Process: com.example.odata, PID: 28391
E/AndroidRuntime(28391): org.apache.olingo.client.api.http.HttpClientException: android.os.NetworkOnMainThreadException
E/AndroidRuntime(28391): at org.apache.olingo.client.core.communication.request.AbstractODataRequest.doExecute(AbstractODataRequest.java:312)
So it looks like it is running on the main thread - which is a no go as this would block. I tried the looper to ask Java to run on the UI Thread:
public void onMethodCall(MethodCall call, Result result) {
// Note: this method is invoked on the main thread.
Log.i("test", "using " + call.method);
String serviceUrl = "http://services.odata.org/OData/OData.svc/";
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
if (call.method.equals("getMetaData")) {
String metadata;
final Edm edm = ODataClientFactory.getClient().getRetrieveRequestFactory().getMetadataRequest(serviceUrl).execute().getBody();
metadata = edm.toString();
if (metadata != "") {
result.success(metadata);
} else {
result.error("UNAVAILABLE", "Metadata cannot read.", null);
}
} else {
result.notImplemented();
}
}
});
But Im still getting the same error.
So how exactly can I deal with external JAR Library which are doing blocking operations ? To my understanding an external call is a Future anyway so it will not block my Flutter thread anyway - but Android Java does not think so ...
This is my method call in flutter
Future<void> _getMetaData() async {
String metadata;
try {
final String result = await platform.invokeMethod('getMetaData');
metadata = result;
} on PlatformException catch (e) {
metadata = e.message;
}
setState(() {
_metadata = metadata;
});
}
Thanks for the answer, this is the solution for anyone that may be interested:
public void onMethodCall(MethodCall call, Result result) {
if (call.method.equals("getMetaData")) {
class MetadataLoader extends AsyncTask<String , Integer, String> {
#Override
protected String doInBackground(String... urls) {
// call your Java library method here, including blocking methods
return your_return_value;
}
protected void onPostExecute(String _result) {
// your_return_value is now passed in _result
result.success(_result);
}
}
new MetadataLoader().execute(); // Start the Async
}
On the flutter side,
Future<void> _getMetaData() async {
String metadata;
try {
final String result = await platform.invokeMethod('getMetaData');
// do something with the result
// the Flutter thread will stop at the await and resume when the Java
// will call result.success
}
}
You will need to create a new Java thread or Worker. (Note that the "main" thread and the "UI" thread are the same thing - so by posting to the main looper you've ended up in the same place - trying to do network i/o on the main thread.)
Yes, the Flutter engine is running in different threads, but you still need to leave the main native thread unblocked as it is responsible for detecting user input, etc.
Also note that when your blocking activity completes - on its non-main thread - it will likely want to deliver the response to Dart. To do this it will need to use part of your code above - to post the results back to the main thread, which can then invoke method channel operations.
You'll probably want to use your method channel bi-directionally. From flutter to native to request an operation (returning, say, a sequence number), and from native to flutter to deliver the results (quoting the sequence number so that the result can be tied back to the request).

How to pass native headers to disconnect event?

I've been trying to pass native headers to disconnect event using StompJS but I don't know how to declare them (I guess it must be a similar approach like for connect event described here: http://www.sergialmar.com/2014/03/detect-websocket-connects-and-disconnects-in-spring-4/)
The event listener looks following:
#Component
public class DocumentStompDisconnectEvent implements ApplicationListener<SessionDisconnectEvent> {
#Override
#EventListener
public void onApplicationEvent(SessionDisconnectEvent event) {
StompHeaderAccessor sha = StompHeaderAccessor.wrap(event.getMessage());
String documentId = sha.getNativeHeader("documentId").get(0);
System.out.println("Disconnect event [documentId: " + documentId + "]");
}
}
When I try to pass those headers to connect event, then it works fine:
function connect() {
stompClient = Stomp.over(socket);
stompClient.connect({userId: "${userId}", documentId: "${documentId}"}, function (frame) {
but at the moment I don't have any idea how to pass them to disconnect event.

Working with static method Asp.Net

Good night guys!
I'm having the following problem ...
I have a web application that runs a "thread" that takes messages from the queue (MSMQ) ... Everything works correctly .. the problem is when I get this message, I can not display .. because the method that returns the message content is a "static" ..
I need to perform a function in JS to display this message.
conclusion:
The method "ProcessMessage" can not be named because he is not a static method ...
My main goal is to call a function in JS passing as parameter (m.Body.ToString ()) which is the content of the message.
Can anyone help me?
Thank you for sharing your knowledge!
This is my code.
public void StartThread()
{
try
{
while (true)
{
PrepareQueue();
}
}
catch (Exception)
{ }
}
public static void PrepareQueue()
{
MessageQueue myQueue = new MessageQueue(".\\private$\\CTIQueue");
myQueue.Formatter = new XmlMessageFormatter(new Type[] { typeof(String) });
// Add an event handler for the ReceiveCompleted event.
myQueue.ReceiveCompleted += new ReceiveCompletedEventHandler(MyReceiveCompleted);
// Define wait handles for multiple operations.
WaitHandle[] waitHandleArray = new WaitHandle[10];
for (int i = 0; i < 10; i++)
{
// Begin asynchronous operations.
waitHandleArray[i] = myQueue.BeginReceive().AsyncWaitHandle;
}
// Specify to wait for all operations to return.
WaitHandle.WaitAll(waitHandleArray);
return;
}
private static void MyReceiveCompleted(Object source, ReceiveCompletedEventArgs asyncResult)
{
try
{
Thread.Sleep(2000);
MessageQueue mq = (MessageQueue)source;
// End the asynchronous receive operation.
System.Messaging.Message m = mq.EndReceive(asyncResult.AsyncResult);
ProcessMessage(m.Body.ToString()); <-- MY PROBLEM
}
catch (MessageQueueException)
{ }
return;
}
public void ProcessMessage(string message)
{
ScriptManager.RegisterStartupScript(this, GetType(), "popup", "NewCaller('" + message + "');", true);
}
Why not instantiate an object of the class and call ProcessMessage on it? Static methods can instantiate an object of the enclosing class and invoke instance methods on it.
private static void MyReceiveCompleted(Object source, ReceiveCompletedEventArgs asyncResult)
{
try
{
Thread.Sleep(2000);
MessageQueue mq = (MessageQueue)source;
// End the asynchronous receive operation.
System.Messaging.Message m = mq.EndReceive(asyncResult.AsyncResult);
new MyClass().ProcessMessage(m.Body.ToString()); <-- MY PROBLEM
}
catch (MessageQueueException)
{ }
return;
}
But if you are planning to invoke a client side code from server side, with reactive action happening at the server's end(which I think is your case) -- then I would prefer you use ASP.NET SignalR to signal the client that something interesting has happened at the server's end.

WF 4 OnUnhandledException not hit

I've created a custom activity which contains as a Body another Activity.
[Browsable(false)]
public Activity Body { get; set; }
protected override void Execute(NativeActivityContext context)
{
ActivityInstance res = context.ScheduleActivity(Body, new CompletionCallback(OnExecuteComplete), OnFaulted);
}
private void OnFaulted(NativeActivityFaultContext faultContext, Exception propagatedException, ActivityInstance propagatedFrom)
{
throw new Exception(propagatedException.Message);
}
When an exception is thrown during the execution of the Body, ma handler for the OnFaulted is hit.
My execution starts with a call to static method Run of the WorkflowApplication class. My WorkflowApplication instance has a handler associated for the OnUnhandledException event.
instance.OnUnhandledException +=
delegate(WorkflowApplicationUnhandledExceptionEventArgs args)
{
Console.WriteLine(args.ExceptionSource);
waitEvent.Set();
return UnhandledExceptionAction.Cancel;
};
But regardless of what happens when the Activity hosted in the Body is executed, i never reach the handler defined above. I thought that if i throw an exception from the OnFaulted, i will be able to redirect the flow to the OnUnhandledException but i was wrong. Any ideas ?
I need this in order to centralize my errors, check them and display messages accordingly. Also i need a way to stop the execution and so on and i don't want to define handlers all over the application. Is there any way to accomplish this ?
As Will suggested, i will post what i did to handle my scenario.
Basically, in my custom activity i have hosted an Assign :
[Browsable(false)]
public Activity Body { get; set; }
Activity System.Activities.Presentation.IActivityTemplateFactory.Create(System.Windows.DependencyObject target)
{
return new Assignment()
{
Body = new Assign() { DisplayName = "" }
};
}
I've added this code to my Execute method :
ActivityInstance res = context.ScheduleActivity(Body, new CompletionCallback(OnExecuteComplete), OnFaulted);
I was trying to run this Assignment by giving an array a negative value as index and and an exception was thrown. This, somehow ended my execution but no handler for the events of my WorkflowApplication instance were hit.
Here is the method given as a callback when executing the body ( in our case the Assign activity ) :
private void OnFaulted(NativeActivityFaultContext faultContext, Exception propagatedException, ActivityInstance propagatedFrom)
{
faultContext.HandleFault();
CommunicationExtension ce = faultContext.GetExtension<CommunicationExtension>();
ITextExpression toTextExpression = (propagatedFrom.Activity as Assign).To.Expression as ITextExpression;
string valueTextExpression = string.Empty;
if ((propagatedFrom.Activity as Assign).Value != null)
{
if ((propagatedFrom.Activity as Assign).Value.Expression != null)
valueTextExpression = (propagatedFrom.Activity as Assign).Value.Expression.ToString();
}
if (ce != null)
{
ce.AddData(string.Format("{0} found on Assignment definition [{1} = {2}]", propagatedException.Message, toTextExpression.ExpressionText, valueTextExpression));
}
}
The trick was to call :
faultContext.HandleFault();
and use CommunicationExtension to allow me to to display the erros in the GUI.
The code for this class is trivial :
public class CommunicationExtension
{
public List<string> Messages { get; set; }
public CommunicationExtension()
{
Messages = new List<string>();
}
public void AddData(string message)
{
if (string.IsNullOrEmpty(message))
return;
Messages.Add(message);
}
}
Use this to add the extension:
CommunicationExtension ce = new CommunicationExtension();
instance.Extensions.Add(ce);
where instance is my WorkflowApplication instance.
I understood that for each instance of the workflow application we have one instance of its extension class. So i can send messages like this from all my custom activities in order to display their status.
I hope this scenario can help other people too.

Synchronous responses to `Gdx.net.sendHttpRequest` in LibGDX

I'm making a small game in LibGDX. I'm saving the player's username locally as well as on a server. The problem is that the application is not waiting for the result of the call so the online database's ID is not saved locally. Here's the overall flow of the code:
//Create a new user object
User user = new User(name);
//Store the user in the online database
NetworkService networkService = new NetworkService();
String id = networkService.saveUser(user);
//Set the newly generated dbase ID on the local object
user.setId(id);
//Store the user locally
game.getUserService().persist(user);
in this code, the id variable is not getting set because the saveUser function is returning immediately. How can I make the application wait for the result of the network request so I can work with results from the server communication?
This is the code for saveUser:
public String saveUser(User user) {
Map<String, String> parameters = new HashMap<String, String>();
parameters.put("action", "save_user");
parameters.put("json", user.toJSON());
HttpRequest httpGet = new HttpRequest(HttpMethods.POST);
httpGet.setUrl("http://localhost:8080/provisioner");
httpGet.setContent(HttpParametersUtils.convertHttpParameters(parameters));
WerewolfsResponseListener responseListener = new WerewolfsResponseListener();
Gdx.net.sendHttpRequest (httpGet, responseListener);
return responseListener.getLastResponse();
}
This is the WerewolfsResponseListener class:
class WerewolfsResponseListener implements HttpResponseListener {
private String lastResponse = "";
public void handleHttpResponse(HttpResponse httpResponse) {
System.out.println(httpResponse.getResultAsString());
this.lastResponse = httpResponse.getResultAsString();
}
public void failed(Throwable t) {
System.out.println("Saving user failed: "+t.getMessage());
this.lastResponse = null;
}
public String getLastResponse() {
return lastResponse;
}
}
The asynchrony you are seeing is from Gdx.net.sendHttpRequest. The methods on the second parameter (your WerewolfsResponseListener) will be invoked whenever the request comes back. The success/failure methods will not be invoked "inline".
There are two basic approaches for dealing with callbacks structured like this: "polling" or "events".
With polling, your main game loop could "check" the responseListener to see if its succeeded or failed. (You would need to modify your current listener a bit to disambiguate the success case and the empty string.) Once you see a valid response, you can then do the user.setId() and such.
With "events" then you can just put the user.setId() call inside the responseListener callback, so it will be executed whenever the network responds. This is a bit more of a natural fit to the Libgdx net API. (It does mean your response listener will need a reference to the user object.)
It is not possible to "wait" inline for the network call to return. The Libgdx network API (correctly) assumes you do not want to block indefinitely in your render thread, so its not structured for that (the listener will be queued up as a Runnable, so the earliest it can run is on the next render call).
I would not recommend this to any human being, but if you need to test something in a quick and dirty fashion and absolutely must block, this will work. There's no timeout, so again, be prepared for absolute filth:
long wait = 10;
while(!listener.isDone())
{
Gdx.app.log("Net", "Waiting for response");
try
{
Thread.sleep(wait *= 2);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
public static class BlockingResponseListener implements HttpResponseListener
{
private String data;
private boolean done = false;
private boolean succeeded = false;
#Override
public void handleHttpResponse(HttpResponse httpResponse)
{
Gdx.app.log("Net", "response code was "+httpResponse.getStatus().getStatusCode());
data = httpResponse.getResultAsString();
succeeded = true;
done = true;
}
#Override
public void failed(Throwable t)
{
done = true;
succeeded = false;
Gdx.app.log("Net", "Failed due to exception ["+t.getMessage()+"]");
}
public boolean succeeded()
{
return succeeded;
}
public boolean isDone()
{
return done;
}
public String getData()
{
return data;
}
}

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