Referring to MediaPlayer Breaks Script? NullPointerException (JavaFX)

Question

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
    at game.updateLocation(game.java:52)
    at worldMap.startGame(worldMap.java:72)
    at gameRun.lambda$start$0(gameRun.java:63)
    at gameRun$$Lambda$1/424873723.handle(Unknown Source)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.event.Event.fireEvent(Event.java:204)
    at javafx.scene.Node.fireEvent(Node.java:8175)
    at javafx.scene.control.Button.fire(Button.java:185)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:204)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3746)
    at javafx.scene.Scene$MouseHandler.access$1800(Scene.java:3471)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1695)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2486)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:314)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:243)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:345)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:526)
    at com.sun.glass.ui.View.notifyMouse(View.java:898)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39)
    at com.sun.glass.ui.win.WinApplication$4$1.run(WinApplication.java:112)
    at java.lang.Thread.run(Thread.java:745)

The trigger for the following code is from gameRun.java:

worldMap map = new worldMap();
map.startGame(game);

Is the error I get when I attempt to click the play button. The code snippet in worldMap.java is as follows

Location YourHometown, Beach;
Location newLocation;
public void createLocations()
{
    YourHometown = new Location("Your Hometown", "Everyone smiles here and talks about sunshines and rainbows. It has a familiar scent of roasted pigs and handknit socks.", "YourHometown.mp3", "Town");
    newLocation = YourHometown;
    Beach = new Location("Beach", "It's Beachy", "Beach.mp3", "Zone");
}

public void startGame(game Game)
{
    createLocations();
    Game.updateLocation(newLocation);
}

And Game.updateLocation() refers to game.java

public void updateLocation (Location newLocation){
...
}

Location is its own separate class, and is an Object. ideally, what this code is supposed to do is change newLocation every time a button with a different Location than the current one is pressed. The objective of the code displayed is to set the default Location to the YourHometown Location Object.

However, the code breaks once we run Game.updateLocation(newLocation); with the following error, and though I know what a NullPointerException is, I don't know how to fix it in the given JavaFX context.

My reasoning is in order for the code to run, the code is forced into createLocations(); with the startGame() method, so there shouldn't ever be a reason why newLocation is null (Since newLocations is set equal to YourHometown). To test my logic, I ran the following code under startGame(), and it still returned the same error:

public void startGame(game Game)
{
    createLocations();
    if(newLocation != null)
    {
        Game.updateLocation(newLocation);
    }
    else
    {
        System.out.println("Break");
    }
}

The console did not print the "Break" line, meaning that newLocation is indeed not null, but the script for updateLocation() runs and the error is returned

TL;DR Conclusion

public void updateLocation (Location newLocation){
    if(bgm.getStatus().equals(Status.PLAYING))
    {
        timeline = new Timeline(new KeyFrame(Duration.seconds(2), new KeyValue(bgm.volumeProperty(), 0)));
        timeline.play();
        bgm.stop();
    }

    bg = new Media(new File(newLocation.getMusic()).toURI().toString());
    bgm = new MediaPlayer(bg);
    bgm.play();

    timeline = new Timeline(new KeyFrame(Duration.seconds(2), new KeyValue(bgm.volumeProperty(), 1)));
    timeline.play();
}

Everything is supposedly working except for the method given above. I think this might be some sort of File/Mediaplayer issue, but I don't know how to approach solving it. The function for updateLocation()is supposed to be a smooth transition from the music in the previous location to the next (previous music fade out --> nextLocation music fade in). It calls the .mp3 files that are located in the same folder that the script is in.

Any help is appreciated, and I can include any extra info if it is missing. I tried simplifying it to make it less of a read.

score 0 · Answer 1 · answered May 20 '17 at 22:18

0

When you call

map.startGame(game);

game is null. I can't see if you assign any value to it from the code you pasted.

answered May 20 '17 at 22:18

ekaerovets

1,158
10
18

game game = new game(); I've excluded it from the code displayed. Refer to the Conclusion; that's where the issue is located. – ArQane - ArQ May 20 '17 at 22:20
@ArQane-ArQ are you sure that new game() is called prior to map.startGame()? – ekaerovets May 20 '17 at 22:21
It's there. The issue is strictly located in the given method updateLocation() – ArQane - ArQ May 20 '17 at 22:27
@ArQane-ArQ I see now. What's the line 52 in class game? – ekaerovets May 20 '17 at 22:30
timeline = new Timeline(new KeyFrame(Duration.seconds(2), new KeyValue(bgm.volumeProperty(), 0))); From updateLocation() – ArQane - ArQ May 20 '17 at 22:31
@ArQane-ArQ the only thing that may throw NPE is bgm.volumeProperty(), but this is very unlikely because you call bgm.getStatus() right before. May it be that you've modified your code and stackTrace shows another line number? – ekaerovets May 20 '17 at 22:43
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/144749/discussion-between-arqane-arq-and-ekaerovets). – ArQane - ArQ May 20 '17 at 22:57
From the stack trace, `game` cannot possibly be null. – James_D May 20 '17 at 22:59

Referring to MediaPlayer Breaks Script? NullPointerException (JavaFX)

1 Answers1