I want obey the MVVM struct in an android app. Now I have a situaion:
I want repeat get data from net and update the view.
So my code is like this:
public class FooVm() {
private MutalbeLiveData<Data> data = new MutableLiveData();
private Timer timer;
public LiveData<Data> getData() {
if (data == null) {
data = new MutableLivedata();
repeatRefresh()
}
}
private void repeatRefersh() {
timer = new Timer();
// schedule at fixed rate get data from net.
}
#override
public void onClear() {
if (timer == null) {
timer.cancel();
timer = null;
}
}
}
Now question is: if I want pause refresh when then view(for example, an Activity) onStop and resume refresh when view onStart. What's the right way to do thi?
Create another methods in viewModel , stopTimer() and resumeTimer()
override onStop() and onResume() in the activity
call viewModel.stopTimer() and viewModel.resumeTimer() before super method.
override fun onStop() {
viewModel.stopTimer()
super.onStop()
}
override fun onResume(){
viewModel.resumeTimer()
super.onResume()
}
I write it in kotlin . but you get the idea.
Related
I try to exit 'lock task mode' in Xamarin Android app. Here is what I am trying to achieve:
User taps on label (view in Xamarin.Forms) -> it cause change in ViewModel's boolean property to true
MainActivity (Xamarin.Android) observe that property has changed to true -> it makes application exit 'lock task mode'
My viewModel is placed in Xamarin.Forms 'App.xaml' class so it is accessible in Forms and Android part.
How Can I notify my Activity that property has changed so it can exit locked mode? I know this is propably very poor workaround, I would love to hear any advices and tips to make it more professional.
Thank you in advance!
EDIT
So the point is that I have got ViewModel with boolean property exitLockMode which indicates if app should be in lock mode or not:
public class AdminViewModel : BaseViewModel
{
//Number of taps to touch at main banner in 'MainPage' to open Admin Window
private int _tapsRequiredToAdmin = 5;
//Number of tolerance in miliseconds between next taps
private int _toleranceInMs = 1000;
private bool _exitLockMode = false;
public int ToleranceInMs { get => _toleranceInMs; }
public int TapsRequiredToAdmin { get => _tapsRequiredToAdmin; }
public bool ExitLockMode
{
get => _exitLockMode;
set => _exitLockMode=value;
}
}
AdminViewModel is created in 'App.xaml' class:
public partial class App : Application
{
private static AdminViewModel _adminViewModel;
public App()
{
InitializeComponent();
MainPage = new NavigationPage(new MainPage());
}
public static AdminViewModel AdminViewModel
{
get
{
if(_adminViewModel == null )
_adminViewModel = new AdminViewModel();
return _adminViewModel;
}
}
protected override void OnStart() { }
protected override void OnSleep() { }
protected override void OnResume() { }
}
In my main view (Xamarin.Forms) I have got label where admin want to tap few times in order to exit lock mode:
private DateTime? LastTap = null;
private byte NumberOfTaps = 0;
AdminViewModel adminViewModel = App.AdminViewModel;
**********************************************
//This is method binded to Label in <TapGestureRecognizer Tapped="OnLabelTapped">
private async void OnLabelTapped(object sender, EventArgs e)
{
if (LastTap == null || (DateTime.Now - LastTap.Value).TotalMilliseconds < adminViewModel.ToleranceInMs)
{
if (NumberOfTaps == (adminViewModel.TapsRequiredToAdmin - 1))
{
NumberOfTaps = 0;
LastTap = null;
adminViewModel.ExitLockMode = true;
return;
}
else
{
NumberOfTaps++;
LastTap = DateTime.Now;
}
}
else
{
NumberOfTaps = 1;
LastTap = DateTime.Now;
}
}
Now I want to achieve that when I turn 'ExitLockMode' bool to true, it notify my 'MainActivity' (Xamarin.Android) to fire 'StopLockTask()' method. I know that in native Android it could be handled by observing bool property, but I don't know how to do it here.
I am newbie so it could be very messy, every help appreciated.
As Jason said, you can use messagecenter.The Xamarin.Forms MessagingCenter class implements the publish-subscribe pattern, allowing message-based communication between components that are inconvenient to link by object and type references.
This mechanism allows publishers and subscribers to communicate without having a reference to each other, helping to reduce dependencies between them.
You can follow this document and the sample in it https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/messaging-center
I want to run a task in background updating intermediate results in the view.I am trying to implement MVC JavaFX application. The task is defined in the Model.
I want to send to the main threath partial results in order to show them in the View.
I use updateValue() to do so. Also, I define object property and a listener in the controller.
My problem: The method changed() from the listener, is not being fired each time that updateValue() is executed in the Task. Why? How can I force it to do this?.
I have not found much complex examples.
What I have so far:
Model.cpp
ComplexObject _complexO;
public Task<ComplexObject> getModelTask() {
return new Task<ComplexObject>() {
#Override
protected ComplexObject call() throws Exception {
int numberOfFiles = 0;
boolean filesToRead = true;
while (filesToRead){
// ....
_complexO = new ComplexObject();
try{
//..
if(f.exists()){
_complexO.initialize();
numberOfScans ++;
}
else{
_complexO.initializeToNull();
}
String stringNumber = Converter.toString(numberOfFiles);
updateMessage(stringNumber);
updateValue(_complexO );
} catch(Exception ex){
ex.printStackTrace();
_complexO = null;
return _complexO;
}
filesToRead = areThereFilesToRead();
}
return _complexO;
}
};
}
Controller.cpp
...
Task< ComplexObject> task = _model.getModelTask();
_AJavaFXTextField.textProperty().bind(task.messageProperty());
_AJavaFXTextField.textProperty().addListener(new ChangeListener<String>() {
#Override
public void changed(ObservableValue observable, String oldValue, String newValue) {
System.out.println("Success with messageProperty!!" + newValue);
}
});
SimpleObjectProperty<ComplexObject> complexObjectProperty = new SimpleObjectProperty<>();
complexObjectProperty.bind(task.valueProperty());
complexObjectProperty.addListener(new ChangeListener<ComplexObject>(){
#Override
public void changed(ObservableValue<? extends ComplexObject> observable, ComplexObject oldValue, ComplexObject newValue) {
if(newValue.data == null ) {
System.out.println("value is new!!! " + scansNumber);
}
else if(newValue.isValid()){
System.out.println("I want to plot newValue data here");
}
}
});
Thread th= new Thread(task);
System.out.println("call TASK");
th.start();
}
My questions/conclusions here:
How to force to all times that I execute in the task updateValue() to really execute the listener - so execute the code where I want to plot data.
Why it is more times fire the bind for the messageProperty than the valueProperty? - it should be the same number of times.
Why I find that the code of the listener is fired more times when debug mode than normal execution?
Any recomendation of good sources about this topic (from a complex point of view) would be great.
I am looking from something in JavaFX to replace SwingWorker.
What I really whant at the end: To return a list of complexObjects from the task, and ideally, updateValue() would send the objects one per one (partial results)
I have followed:
https://docs.oracle.com/javase/8/javafx/api/javafx/concurrent/Task.html
Thanks very much for any contribuction
Task only guaranties that a value passes to updateValue or a value passed later will be set to the value property. This is done to increase performance of the application thread by limiting the number of changes the listeners are notified of.
Why it is more times fire the bind for the messageProperty than the valueProperty? - it should be the same number of times.
As described above there simply is no guaranty about the number of updates.
Why I find that the code of the listener is fired more times when debug mode than normal execution?
In general debugging makes your program smaller. The smaller the update frequency from the thread of your Task, the smaller the number of updates between the times the Task class updates the properties and the smaller the number of skipped. (The updates are probably executed every frame or every few frames.) If you even use a break-point/stepper in the task, you probably make the Task extremely slow while the application thread runs at normal speed.
It should be easy enough to implement publish on your own by using a List to buffer the updates
public abstract class JavaFXWorker<S, T> extends Task<S> {
private List<T> chunks = new ArrayList<>();
private final Object lock = new Object();
private boolean chunkUpdating = false;
protected final void publish(T... results) {
synchronized (lock) {
chunks.addAll(Arrays.asList(results));
if (!chunkUpdating) {
chunkUpdating = true;
Platform.runLater(() -> {
List<T> cs;
synchronized (lock) {
cs = chunks;
// create new list to not unnecessary lock worker thread
chunks = new ArrayList<>();
chunkUpdating = false;
}
try {
process(cs);
} catch (RuntimeException ex) {
}
});
}
}
}
protected void process(List<T> chunks) {
}
}
Sample use
#Override
public void start(Stage primaryStage) {
ListView<Integer> lv = new ListView<>();
Button btn = new Button("Run");
btn.setOnAction((ActionEvent event) -> {
JavaFXWorker<Void, Integer> worker = new JavaFXWorker<Void, Integer>() {
#Override
protected Void call() throws Exception {
final int maxCount = 100;
Random random = new Random();
int breakIndex = random.nextInt(maxCount-1)+1;
for (int i = 0; i < breakIndex; i++) {
publish(i);
}
// some break simulating a part long part of the task with no updates
Thread.sleep(3000);
for (int i = breakIndex; i <= maxCount; i++) {
publish(i);
}
return null;
}
#Override
protected void process(List<Integer> chunks) {
lv.getItems().addAll(chunks);
}
};
new Thread(worker).start();
});
Scene scene = new Scene(new VBox(btn, lv));
primaryStage.setScene(scene);
primaryStage.show();
}
Do you know how to wait for the user's input in a for loop? I don't mean the showAndWait() method, because I am not opening a new dialogue stage for the user. So for example, each round of the for loop should be waiting for the user to push a button before going ahead with the next round.
How is it possible? Many thanks!
UPDATE:
Now it came to my mind, that it would work with a while(buttonNotPressed){} but is it a good solution? I mean the while loop is running in this case as crazy until the user won't push the button. Or doest it work somehow similarly with wait methods?
Imagine it as a session:
User starts session with handleStart() You give the user 5 questions, one after one. In every iteration, the user can answer the upcoming question and he can save or submit the answer by handleSaveButton() You process the answer as you want, and go ahead with the next iteration. The point is, that the iteration must stop, until the save button hasn't been pressed.
Don't do it like that. The FX toolkit, like any event-driven GUI toolkit, already implements a loop for the purposes of rendering the scene graph and processing user input each iteration.
Just register a listener with the button, and do whatever you need to do when the button is pressed:
button.setOnAction(event -> {
// your code here...
});
If you want the action to change, just change the state of some variable each time the action is performed:
private int round = 0 ;
// ...
button.setOnAction(event -> {
if (round < 5) {
System.out.println("Round "+round);
System.out.println("User's input: "+textArea.getText());
round++ ;
}
});
I recently ran into a similar problem where I wanted something to be executed with an interval (if that's what you mean), until the user fired an event. I found 3 ways to do this:
UPDATE
You should use the stop/cancel method for the custom runnable and timer or else the thread will still be running when you exit the application. Timeline seems do it by itself.
Using a Timer:
Timer timer = new Timer();
TimerTask task = new TimerTask() {
#Override
public void run() {
System.out.println("Printed every second.");
}
};
timer.scheduleAtFixedRate(task, 0, 1000);
//timer.cancel();
With a TimeLine:
Timeline tl = new Timeline(new KeyFrame(Duration.millis(1000), e -> {
System.out.println("Timeline");
}));
tl.setCycleCount(Timeline.INDEFINITE);
tl.play();
//tl.stop();
Or making your own runnable class:
public class Runner implements Runnable {
private final Thread thread = new Thread(this);
private boolean run;
#Override
public void run() {
while(run) {
try {
System.out.println("Printed from loop");
Thread.sleep(1000);
} catch (InterruptedException e) {
run = false;
}
}
}
public void start() {
run = true;
thread.start();
}
public void stop() {
if(run) {
thread.interrupt();
System.out.print("Thread has stopped.");
}
}
}
And then when a person clicks fx. a button the event would stop using the example James_D posted:
Button btn = new Button("Button");
btn.setOnAction(e -> {
timer.cancel();
tl.stop();
runner.stop();
});
In my case, for inside for, had to create 2 index in class, use:
//start method
Timer timer = new Timer();
TimerTask task = new TimerTask()
{
public void run()
{
Platform.runLater(()->{
//... code to run after time, calling the same mehtod, with condition to stop
});
}
};
timer.schedule(task, time);
//end method
Had to use recursive method, incrementing the index with conditions, cause the tasks were been schedule all at the same time, without wait time.
I do not know if it is rigth, but was the solution that i found.
Hope it helps.
ALTERNATIVE SOLUTION W/O PAUSING:
I'm creating a game where I want the user to pick the game difficulty before the game starts. Instead of trying to pause the program midway through, I just put the next step of the code in a separate method which you call once a button is clicked:
private static difficulty;
public static void main(String[] args) {
try {
Application.launch(args);
} catch (UnsupportedOperationException e) {
}
}
public void start(Stage startStage) {
HBox buttons = new HBox();
Button easyButton = new Button("Easy");
Button mediumButton = new Button("Medium");
Button hardButton = new Button("Hard");
buttons.getChildren().addAll(easyButton, mediumButton, hardButton);
buttons.setAlignment(Pos.CENTER);
hbox.getChildren().addAll(buttons);
Scene startScene = new Scene(buttons, 200, 200);
startStage.setScene(startScene);
startStage.show(); // MENU
EventHandler<ActionEvent> playEasy = new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent actionEvent) {
difficulty = 1; // SET DIFFICULTY
startStage.close(); // CLOSE MENU
play(); // RUN GAME ON EASY
}
};
EventHandler<ActionEvent> playMedium = new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent actionEvent) {
difficulty = 2; // SET DIFFICULTY
startStage.close(); // CLOSE MENU
play(); // RUN GAME ON MEDIUM
}
};
EventHandler<ActionEvent> playHard = new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent actionEvent) {
difficulty = 3; // SET DIFFICULTY
startStage.close(); // CLOSE MENU
play(); // RUN GAME ON HARD
}
};
easyButton.setOnAction(playEasy);
mediumButton.setOnAction(playMedium);
hardButton.setOnAction(playHard);
}
public void play() {
// WRITE GAME CODE HERE
}
To solve your specific problem, you could probably pass the startStage into the play method and then just update the scene there...but regardless I do hope this helps someone whos having trouble on how to use buttons! :)
Since I couldn't find any specific place to discuss this, I thought I'd post here...
I'm using graphstream 1.1 (http://graphstream-project.org/), a graph visualization library for java, to develop a data visualization tool. I'm needing to retrieve mouseclicks on nodes to display related data, but after following the library tutorial, it's still not clear for me how to do this. Does anyone that used this could help me out here with a more straightfoward answer? The tutorial I'm following is at:
http://graphstream-project.org/doc/Tutorials/Graph-Visualisation_1.0/#retrieving-mouse-clicks-on-the-viewer
public class Clicks implements ViewerListener {
protected boolean loop;
public static void main(String args[]) {
new Clicks();
}
public Clicks() {
// We do as usual to display a graph. This
// connect the graph outputs to the viewer.
// The viewer is a sink of the graph.
Graph graph = new SingleGraph("Clicks");
Viewer viewer = graph.display();
// The default action when closing the view is to quit
// the program.
viewer.setCloseFramePolicy(Viewer.CloseFramePolicy.HIDE_ONLY);
// We connect back the viewer to the graph,
// the graph becomes a sink for the viewer.
// We also install us as a viewer listener to
// intercept the graphic events.
ViewerPipe fromViewer = viewer.newViewerPipe();
fromViewer.addViewerListener(this);
fromViewer.addSink(graph);
// Then we need a loop to wait for events.
// In this loop we will need to call the
// pump() method to copy back events that have
// already occured in the viewer thread inside
// our thread.
while(loop) {
fromViewer.pump();
}
}
viewClosed(String id) {
loop = false;
}
buttonPushed(String id) {
System.out.println("Button pushed on node "+id);
}
buttonReleased(String id) {
System.out.println("Button released on node "+id);
}
}
Just got it solved! I sent an e-mail to their mailing group. The tutorial code on the website was lacking some information. Those three functions need to be public void, and other 'imports' must be added:
import org.graphstream.ui.swingViewer.Viewer;
import org.graphstream.ui.swingViewer.ViewerListener;
import org.graphstream.ui.swingViewer.ViewerPipe;
Here a simple code to show you how to add click event to the nodes of a given graph in graphstream library. This code show how you can change the node's background by clicking on it. The colors are choosen randomly:
public class TutoMouseClicked{
Graph graph;
public TutoMouseClicked(){
}
public void run(){
//Build a simple graph with one node
graph = new SingleGraph("TutoMouseClicked", false, true);
graph.setAttribute("ui.quality");
graph.setAttribute("ui.antialias");
Node n1 = graph.addNode("n1");
n1.setAttribute("ui.style", "size: 100px;");
Viewer viewer = graph.display();
viewer.getDefaultView().setMouseManager(new TutoMouseManage());
}
public static void main(String args[]) {
new TutoMouseClicked().run();
}
}
And the class TutoMouseManage that implements MouseManager interface:
public class TutoMouseManage implements MouseManager{
/**
* The view this manager operates upon.
*/
protected View view;
/**
* The graph to modify according to the view actions.
*/
protected GraphicGraph graph;
protected GraphicElement element;
#Override
public void init(GraphicGraph gg, View view) {
this.graph = gg;
this.view = view;
view.addMouseListener(this);
view.addMouseMotionListener(this);
}
#Override
public void release() {
view.removeMouseListener(this);
view.removeMouseMotionListener(this);
}
#Override
public void mouseClicked(MouseEvent me) {
element = view.findNodeOrSpriteAt(me.getX(), me.getY());
if(element != null){
Random r = new Random();
element.setAttribute("ui.style", "fill-color: rgb("+r.nextInt(256)+","+r.nextInt(256)+","+r.nextInt(256)+");");
}
}
#Override
public void mousePressed(MouseEvent me) {
}
#Override
public void mouseReleased(MouseEvent me) {
}
#Override
public void mouseEntered(MouseEvent me) {
}
#Override
public void mouseExited(MouseEvent me) {
}
#Override
public void mouseDragged(MouseEvent me) {
}
#Override
public void mouseMoved(MouseEvent me) {
}
}
you can adapt this code to get what you need, add any other mouse event you want: mouse released, mouse pressed, mouse dragged and all mouse events.
I want to know whether how to capture the button clicked with AspectJ and get its parameter (eg. button name). I think for having more generalized capturing with AspectJ, it shoudl be used MouseListener so it can capture other UI elements in general!
Example:
In a GUI example I have defined 2 buttons that take some actions
public JButton btn1 = new JButton("Test1");
public JButton btn2 = new JButton("Test2");
btn1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
//take some actions
}
}
btn2.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
//take some actions
}
}
How to capture these buttons with AspectJ, and get their parameters (eg. name)?
It is possible. I have provided two examples. The first that prints out for every JButton that has an ActionListener. The other example only prints out if a specific buttons is clicked.
Prints the text for every JButton clicked with an ActionListener:
#Pointcut("execution(* *.actionPerformed(*)) && args(actionEvent)")
public void buttonPointcut(ActionEvent actionEvent) {}
#Before("buttonPointcut(actionEvent)")
public void beforeButtonPointcut(ActionEvent actionEvent) {
if (actionEvent.getSource() instanceof JButton) {
JButton clickedButton = (JButton) actionEvent.getSource();
System.out.println("Button name: " + clickedButton.getText());
}
}
Prints the text for a specific JButton:
public static JButton j1;
#Pointcut("execution(* *.actionPerformed(*)) && args(actionEvent) && if()")
public static boolean button1Pointcut(ActionEvent actionEvent) {
return (actionEvent.getSource() == j1);
}
#Before("button1Pointcut(actionEvent)")
public void beforeButton1Pointcut(ActionEvent actionEvent) {
// logic before the actionPerformed() method is executed for the j1 button..
}
UPDATED:
You can do this in many different ways. For example add your buttons to the aspect directly. But I prefere to use a enum object between (ButtonManager in this case), so the code does not know about the aspect. And since the ButtonManager is an enum object, it is easy for the aspect to retrieve values from it.
I just tested it with a Swing button class from Oracle and it works. In the Swing class:
b1 = new JButton("Disable middle button", leftButtonIcon);
ButtonManager.addJButton(b1);
AspectJ is extremely powerful when it comes to manipulating classes, but it can not weave advises into specific objects since objects is not created at the time of weaving. So you can only work with objects at runtime and that is why I have added the addJButton(..) method above. That enables the aspect to check the advised button against a list of registered buttons.
The ButtonManager class:
public enum ButtonManager {
;
private static Collection<JButton> buttonList = new LinkedList<JButton>();
public static void addJButton(JButton jButton) {
buttonList.add(jButton);
}
public static Collection<JButton> getButtonList() {
return buttonList;
}
}
Modified pointcut and advice to only print the name of the buttons registered in the ButtonManager:
#Pointcut("execution(* *.actionPerformed(*)) && args(actionEvent) && if()")
public static boolean buttonListPointcut(ActionEvent actionEvent) {
Collection<JButton> buttonList = ButtonManager.getButtonList();
JButton registeredButton = null;
for (JButton jButton : buttonList) {
if (actionEvent.getSource() == jButton) {
registeredButton = jButton;
}
}
return registeredButton != null;
}
#Before("buttonListPointcut(actionEvent)")
public void beforeButtonListPointcut(ActionEvent actionEvent) {
JButton clickedButton = (JButton) actionEvent.getSource();
System.out.println("Registered button name: " + clickedButton.getText());
}
UPDATED 2
Okay, I believe I understand what you want. You want to listen to mouse events. That is possible. The downside is that you have to register all your GUI components that you want to listen for clicks with a mouse listener. It is not enough to register the JPanel of the JFrame with a MouseListener. So if you only have registered an ActionListener for your buttons, you also have to add a mouse listener.
I have created a quick solution that works for me. It only shows that it works. I have not tried to make the solution generic with many different GUI objects. But that should be quite easy to refactor in when you have got the basics to work.
In the Swing class:
private class MouseListener extends MouseInputAdapter {
public void mouseClicked(MouseEvent e) {}
}
In the init method of the Swing class:
MouseListener myListener = new MouseListener();
btn1.addMouseListener(myListener);
btn2.addMouseListener(myListener);
In the Aspect class:
#Pointcut("execution(* *.mouseClicked(*)) && args(mouseEvent)")
public void mouseEventPointcut(MouseEvent mouseEvent) {}
#Before("mouseEventPointcut(mouseEvent)")
public void beforeMouseEventPointcut(MouseEvent mouseEvent) {
if (mouseEvent.getSource() instanceof JButton) {
JButton clickedButton = (JButton) mouseEvent.getSource();
System.out.println("aspectJ --> mouseClicked: " + clickedButton.getText());
}
}
This results in the following output in the console:
aspectJ --> mouseClicked: Test1
I hope it helps!