Having this code:

final MediaPlayer result = new MediaPlayer(media);
result.startTimeProperty();


throws an NPE at my system:


Exception in runnable
java.lang.NullPointerException
at javafx.scene.media.MediaPlayer.calculateCycleDuration(MediaPlayer.java:1122)
at javafx.scene.media.MediaPlayer.preReady(MediaPlayer.java:1727)
at javafx.scene.media.MediaPlayer$_PlayerStateListener$1.run(MediaPlayer.java:2251)
at com.sun.javafx.application.PlatformImpl$4$1.run(PlatformImpl.java:179)
at com.sun.javafx.application.PlatformImpl$4$1.run(PlatformImpl.java:176)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:176)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:76)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication$3$1.run(GtkApplication.java:82)
at java.lang.Thread.run(Thread.java:724)


The given media for the player is valid.
On searching the bug, I added a change listener on the status property:

result.statusProperty().addListener(new ChangeListener<Status>() {
  @Override
  public void changed(ObservableValue<? extends Status> observable, Status oldValue, Status newValue) {
    System.out.println("status changed: " + oldValue + " -> " + newValue);
    }
  });


Output:

status changed: null -> READY


I assume this could be the reason for the NPE. I would not expect getting an NPE but the player dealing internally with the status UNKNOWN instead of null (if this is the reason).