问题
I'm working on an JavaFX 8 app right now, where i have a tableView and some textFields above which make it possible to search/filter for certain columns in the tableView. I have added a listener to the textFields, to trigger the filtering automatically when a change is detected. I used the code below to do this.
textField_filterAddress.textProperty().addListener((observable, oldValue, newValue) -> {
doSomething(); // in this case, filter table data and refresh tableView afterwards
});
My question now is: what's the easiest way to integrate some kind of time delay, before the filtering gets triggered? I'd like to wait a few milliseconds, because everytime the user is filtering it's executing a new database query and i don't think this is necessary for every single char that the user puts in. I'd rather wait until he/she finished his input. Is there some kind of feature like this already built into the whole listener thing? Or do i have to implement my own solution? If so, how? I thought about some kind of concurrency solution, so the rest of the software won't freeze during the waiting period. But i thought i'd ask here if there is an easier solution before thinking too much about my own way...
Big thanks in advance!
回答1:
The code below will schedule to do something after a 1 second delay from the last time a text field changes. If the text field changes within that 1 second window, the previous change is ignored and the something is scheduled to be done with the new value 1 second from the most recent change.
PauseTransition pause = new PauseTransition(Duration.seconds(1));
textField.textProperty().addListener(
(observable, oldValue, newValue) -> {
pause.setOnFinished(event -> doSomething(newValue));
pause.playFromStart();
}
);
I didn't test this, but it should work :-)
A more sophisticated solution might be to make use of a "forgetful" ReactFX suspendable event stream. ReactFX based solutions are discussed in the related question:
- Wait before Reacting to a Property Change JavaFX 8
回答2:
Interesting problem, and one which I'm sure others have dealt with. I'm thinking this through for the first time and don't know how practical this suggestion is, but here goes:
Have your text field listeners send a notification to a queue. Then, use a util.TimerTask method that executes at your preferred time interval to process the queue, and use that to build a new filter (or not).
The wait time in the above could be rather varied, so to make it a bit more consistent, send the text field ID with a time stamp and have the Timer run more frequently and only process the new filter if a certain amount of time has elapsed.
There are various concurrency-safe queues that could be used to house the data.
来源：https://stackoverflow.com/questions/34784037/javafx-8-how-to-add-a-timedelay-to-a-listener