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TrackEntry current.next is "<none>" and NullPointerException

yookunka

Hi,

I'm using Spine libgdx runtime and spine version is 3.4.02. I get a NullPointerException in setCurrent method in AnimationState from time to time. I can't really reproduce this exception all the time but sometimes it happens somehow. I'm wondering it's because my animation setting has a problem or there's a bug.

When the exception is thrown, current.animation has an animation but entry is "<none>" and entry.animation is null. I don't know how this "<none>" value is set.

private void setCurrent (int index, TrackEntry entry) {
TrackEntry current = expandToIndex(index);
if (current != null) {
   TrackEntry previous = current.previous;
   current.previous = null;

   if (current.listener != null) current.listener.end(index);
   for (int i = 0, n = listeners.size; i < n; i++)
      listeners.get(i).end(index);

   try {
      entry.mixDuration = data.getMix(current.animation, entry.animation);  <==== This line throws NullPointerException
   }
   catch (NullPointerException npe){
      Gdx.app.log("error", npe.toString());
   }
   if (entry.mixDuration > 0) {
      entry.mixTime = 0;

Actually the direct cause of the exception is the a2 in the following code is null. Could you take a look at what's going on here? I can actually suppress the exception with try catch clause so it's not a big problem, though it would be nice to know why :$

static class Key {
   Animation a1, a2;

   public int hashCode () {
      return 31 * (31 + a1.hashCode()) + a2.hashCode();  <=== this line throws the exception and a2 is null
   }

   public boolean equals (Object obj) {
      if (this == obj) return true;
      if (obj == null) return false;
      Key other = (Key)obj;
      if (a1 == null) {
         if (other.a1 != null) return false;
      } else if (!a1.equals(other.a1)) return false;
      if (a2 == null) {
         if (other.a2 != null) return false;
      } else if (!a2.equals(other.a2)) return false;
      return true;
   }
}

I'm using this "applyPrevious" from the following snippet.
One Frame Attachment Animations
Could it be the cause?

Nate

Is it "<None>" (with start caps)? If so, maybe the Unity Inspector UI is setting an animation?
spine-runtimes/SpineAttributeDrawers.cs at master · EsotericSoftware/spine-runtimes · GitHub

yookunka

No, the value was "<none>" (with a small letter).

Nate

OK. Is setCurrent being called by update or by setAnimation when the NPE happens? You'll probably need to find a way to reproduce the problem, so we can see why it happens.

yookunka

Ok, I figured out why it happens :whew: I don't actually code like the following but it happens in some situations anyhow in my code.

animationState.setAnimation(0, "attack", loop);
animationState.addAnimation(0, "idle", loop, delay);
animationState.addAnimation(0, "idle", loop, delay);  <== if I add the same animation sequentially, the NPE will be thrown

If I code like this, setCurrent being called from update throws the NPE. So I should avoid this situation, right? Or could it be a bug? I can avoid this situation by tweaking my code 😉

Pharan

yookunka लिखा
I'm using Spine libgdx runtime and spine version is 3.4.02.

Nate लिखा
If so, maybe the Unity Inspector UI is setting an animation?

@Nate hey, don't accuse yookunka of using Unity. 😃

That's this line throwing the null reference exception, right? spine-runtimes/AnimationStateData.java at master · EsotericSoftware/spine-runtimes · GitHub

Sounds like AnimationState was trying to mix with a null animation.
Do you always call setAnimation/addAnimation with a string? or do you sometimes use it with an animation reference?
Are you somehow manipulating TrackEntry objects so their animations change or become null?

I think that can be a source of the problem: the TrackEntry exists, but its .animation is null.

yookunka

Pharan लिखा
@[हटाया गया] hey, don't accuse yookunka of using Unity.

hahaha. Yeah, I was like "what relates to Unity here?" when Nate asked you 😃

Pharan लिखा
That's this line throwing the null reference exception, right? spine-runtimes/AnimationStateData.java at master · EsotericSoftware/spine-runtimes · GitHub

Yes, it is.

Pharan लिखा
Do you always call setAnimation/addAnimation with a string?

Yes, I always set animations with a string.

Pharan लिखा
or do you sometimes use it with an animation reference?

No, I don't.

Pharan लिखा
Are you somehow manipulating TrackEntry objects so their animations change or become null?

No, I don't do that at all.

Can you reproduce the same exception if you call addAnimation twice with a same animation like my code?

So there is no advice for this problem? :wonder:

Nate

Oops, I must have got my threads crossed. Sorry, I wouldn't insult a libgdx user like that on purpose! 😉

Wait, you got an NPE but never posted the stacktrace? :wonder:

If I add the applyPrevious stuff and edit SimpleTest1:

state.setAnimation(0, "run", true);
state.addAnimation(0, "jump", true, 2); // Jump after 2 seconds.
state.addAnimation(0, "jump", true, 2); // Jump after 2 seconds.

It works fine. Can you show the error with SimpleTest1?

yookunka

I found the exact reason why it happened. Yeah, as you said that SimpleTest1 works fine even though I called addAnimation sequentially with a same animation, but if you change an animation during the end event of AnimationStateAdapter, it throws the exception.

Here is a code snippet of modified version of SimpleTest1

state.setAnimation(0, "run", false);
state.addAnimation(0, "idle", true, 0);
state.addAnimation(0, "idle", true, 0);  <

---

 This line, actually any animation can cause a problem

state.addListener(new AnimationState.AnimationStateAdapter() {
   @Override
   public void end(int trackIndex) {
      if(!firstTime){
         firstTime = true;
         Gdx.app.log("end animation", "");
         state.setAnimation(0, "jump", true);  <

---

 if you change an animation here, NPE will be thrown
      }
   }
});

Nate लिखा
Wait, you got an NPE but never posted the stacktrace?

Sorry man, my bad :$

Here is a stacktrace

Exception in thread "LWJGL Application" java.lang.NullPointerException
   at com.esotericsoftware.spine.AnimationStateData$Key.hashCode(AnimationStateData.java:87)
   at com.badlogic.gdx.utils.ObjectFloatMap.get(ObjectFloatMap.java:279)
   at com.esotericsoftware.spine.AnimationStateData.getMix(AnimationStateData.java:72)
   at com.esotericsoftware.spine.AnimationState.setCurrent(AnimationState.java:191)
   at com.esotericsoftware.spine.AnimationState.update(AnimationState.java:74)
   at com.esotericsoftware.spine.SimpleTest1.render(SimpleTest1.java:96)
   at com.badlogic.gdx.backends.lwjgl.LwjglApplication.mainLoop(LwjglApplication.java:223)
   at com.badlogic.gdx.backends.lwjgl.LwjglApplication$1.run(LwjglApplication.java:124)

Nate

Aha. We've been doing some upgrading for AnimationState lately. In the dev branch it's safe to change the AnimationState in any of the listeners. I verified your SimpleTest1 change there, works fine.

You could use postRunnable:

state.setAnimation(0, "run", false);
state.addAnimation(0, "idle", true, 0);
state.addAnimation(0, "idle", true, 0); // <

---

 This line, actually any animation can cause a problem

state.addListener(new AnimationState.AnimationStateAdapter() {
   boolean firstTime;

   public void end (int trackIndex) {
      if (!firstTime) {
         firstTime = true;
         Gdx.app.log("end animation", "");
         Gdx.app.postRunnable(new Runnable() {
            public void run () {
               state.setAnimation(0, "jump", true); // <

---

 if you change an animation here, NPE will be thrown
            }
         });
      }
   }
});

Or you could try updating to the dev branch, though it's still in a state of flux as we work through the massive issue #621 and a few other AnimationState issues. Almost done though!

yookunka

Nate लिखा
Or you could try updating to the dev branch, though it's still in a state of flux as we work through the massive issue #621 and a few other AnimationState issues. Almost done though!

Awesome! I don't need this to be fixed right now, so I'll wait for the release. Thank you for your time :happy:

Alexees

Hi there,
we are running Spine-Unity 4.1.0. Wo started seeing this anomaly too. Trying to SetAnimation on the AnimationState results in a <none> TrackEntry. Not sure how to reproduce in our setup because we're firing different animations at different times at the spine animation. Some are triggered through trackentry complete OR end event... If we knew what to look out for we could try to invest the time to figure this out, but guessing would cost us too much time...

When is it that we can get this <none> TrackEntry?

Nate

Note you bumped a 6 year old thread.

TrackEntry ToString returns <none> when TrackEntry animation is null. That only happens when a TrackEntry has been reset

entries are pooled and reused, an entry is reset when it is returned to the pool for later reuse. It sounds like you are keeping a reference to a TrackEntry too long. After the AnimationStateListener dispose event, you should not keep a reference to the TrackEntry.