Make a Sound Clip Play Continuously at Designated Start Time in JavaFx - javafx

Question

I need to make a short m4a sound file play continuously for 30 minutes at a designated start time. I am having difficulty to make it play continuously at the designated start time. When I researched this problem, it seems that I may have to use separate threads within JavaFX to make this work but I was unable to write it with threads such as Platform.runLater. I am also open to not having to use threads to achieve this effect. And I am unable to make it loop continuously for 30 minutes with the MediaPlayer methods provided within JavaFX (https://docs.oracle.com/javafx/2/api/javafx/scene/media/MediaPlayer.html).
Here is my code so far, which is only able to play the sound file once:
package MyAppPackage;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import javafx.scene.text.Text;
import javafx.application.Platform;
import javafx.scene.media.Media;
import javafx.scene.media.MediaPlayer;
import javafx.scene.media.MediaView;
import javafx.util.Duration;
import java.io.File;
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class MyApp extends Application {
private void playAppTone(MediaPlayer mp, ZonedDateTime start, ZonedDateTime stop) {
while(ZonedDateTime.now(ZoneId.of("America/New_York")).isAfter(start) &&
ZonedDateTime.now(ZoneId.of("America/New_York")).isBefore(stop) ) {
mp.setOnEndOfMedia(new Runnable() {
#Override public void run() {
mp.seek(Duration.ZERO);
mp.play(); }
});
mp.setAutoPlay(true);
}
}
#Override
public void start(Stage primaryStage) {
Canvas canvas = new Canvas(400,400);
HBox statusBar = new HBox(new Label("Start the App Tone"));
BorderPane borderPane = new BorderPane(canvas, statusBar, null, null, null);
StackPane root = new StackPane(borderPane);
primaryStage.setScene(new Scene(root));
primaryStage.setTitle("Timed Playback of Sound Clip");
primaryStage.show();
statusBar.setOnMouseClicked((event) -> {
ZoneId zoneId = ZoneId.of( "America/New_York" );
ZonedDateTime appStartTime = ZonedDateTime.now( zoneId );
System.out.println(appStartTime);
ZonedDateTime start = appStartTime.plusMinutes(10);
ZonedDateTime stop = appStartTime.plusMinutes(40);
String path = "media/PlaybackClip.m4a";
Text playStatusText = new Text("A sound clip will be played continuously at the designated time...");
Media media = new Media(new File(path).toURI().toString());
MediaPlayer mp = new MediaPlayer(media);
MediaView mv = new MediaView(mp);
StackPane stackPane = new StackPane();
stackPane.getChildren().add(mv);
stackPane.getChildren().add(playStatusText);
primaryStage.setScene(new Scene(stackPane, 400, 400));
mp.play();
mp.setAutoPlay(true);
/*The Platform.runLater doesn't work
Platform.runLater(() -> {
playAppTone(mp, start, stop);
}); */
});
}
public static void main(String[] args) {
launch(args);
}
}

Answer 1

I would avoid using another thread to implement this. Multiple threads will add unnecessary complexity, especially since everything involved needs to be (or at least can be) executed on the JavaFX Application Thread anyway. Instead, I would use a javafx.animation.Timeline with a delay. Animations keep everything on the FX thread and are a good way to delay or periodically execute (or both) simple actions on said thread.
Here's an example (some explanations in code comments):
import java.time.LocalDateTime;
import java.time.temporal.ChronoUnit;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.StackPane;
import javafx.scene.media.Media;
import javafx.scene.media.MediaPlayer;
import javafx.stage.Stage;
import javafx.util.Duration;
public class App extends Application {
#Override
public void start(Stage primaryStage) {
MediaPlayer player = new MediaPlayer(new Media(/* YOUR MEDIA URL */));
/*
* Set to INDEFINITE since the media may not be long enough to play
* for the entire duration you want to. This will cause the media
* to loop until stopped.
*/
player.setCycleCount(MediaPlayer.INDEFINITE);
Timeline timeline =
new Timeline(
/*
* The first KeyFrame's time is set to Duration.ZERO in order
* to start playing the MediaPlayer immediately after the
* Timeline starts playing.
*/
new KeyFrame(Duration.ZERO, e -> player.play()),
/*
* The next KeyFrame's time is set to however long you want the
* media to play for. When the time elapses this KeyFrame will
* stop the MediaPlayer. Depending on your use case you may want
* to call MediaPlayer#dispose() to release its resources.
*/
new KeyFrame(Duration.minutes(30.0), e -> player.stop())
);
/*
* Set the delay of the Timeline to schedule playing the MediaPlayer
* at some point in the future. The duration used here should be equal
* to the duration between now and whatever wall clock time you want to
* start playing the media.
*
* The delay should be calculated and set just before calling play. If you wait
* then the delay will overshoot the wall clock time you expect the media to
* start playing.
*/
timeline.setDelay(durationUntil(LocalDateTime.now().plusSeconds(10L)));
timeline.play();
// provides some simple feedback
Label statusLabel = new Label();
statusLabel.textProperty().bind(player.statusProperty().asString("Current status: %s"));
primaryStage.setScene(new Scene(new StackPane(statusLabel), 500.0, 300.0));
primaryStage.show();
}
/**
* Computes and returns the duration between {#linkplain LocalDateTime#now() now} and {#code
* then}.
*
* #param then the time to compute the duration until
* #return the duration between now and {#code then}
* #throws IllegalArgumentException if {#code then} is in the past
*/
private static Duration durationUntil(LocalDateTime then) {
/*
* Note: Will use the system Clock which may not be the same Clock
* used to create 'then'. May want to add a way to specify
* a custom java.time.Clock if needed.
*/
LocalDateTime now = LocalDateTime.now();
if (then.isBefore(now)) {
throw new IllegalArgumentException("then < now");
}
// Note: Using javafx.util.Duration, not java.time.Duration
return Duration.millis(now.until(then, ChronoUnit.MILLIS));
}
}