Fix NPE for checking for whether animators should play together

BUG: 29586505
Change-Id: Ic2a67d51d2ac8d5bfb11ed7773c7c7e413cc28c7

2 files changed, 5 insertions, 5 deletions

diff --git a/core/java/android/animation/AnimatorSet.java b/core/java/android/animation/AnimatorSet.java
index 7841d29b5700..053ba7d5fa0a 100644
--- a/core/java/android/animation/AnimatorSet.java
+++ b/core/java/android/animation/AnimatorSet.java
@@ -1064,15 +1064,15 @@ public final class AnimatorSet extends Animator {
     /**
      * @hide
      * TODO: For animatorSet defined in XML, we can use a flag to indicate what the play order
-     * if defined (i.e. sequential or together), then we can use the flag instead of calculate
-     * dynamically.
+     * if defined (i.e. sequential or together), then we can use the flag instead of calculating
+     * dynamically. Note that when AnimatorSet is empty this method returns true.
      * @return whether all the animators in the set are supposed to play together
      */
     public boolean shouldPlayTogether() {
         updateAnimatorsDuration();
         createDependencyGraph();
         // All the child nodes are set out to play right after the delay animation
-        return mRootNode.mChildNodes.size() == mNodes.size() - 1;
+        return mRootNode.mChildNodes == null || mRootNode.mChildNodes.size() == mNodes.size() - 1;
     }
 
     @Override
diff --git a/libs/hwui/PropertyValuesAnimatorSet.cpp b/libs/hwui/PropertyValuesAnimatorSet.cpp
index e416e0c0061d..796c73b9c3e7 100644
--- a/libs/hwui/PropertyValuesAnimatorSet.cpp
+++ b/libs/hwui/PropertyValuesAnimatorSet.cpp
@@ -29,7 +29,6 @@ void PropertyValuesAnimatorSet::addPropertyAnimator(PropertyValuesHolder* proper
     PropertyAnimator* animator = new PropertyAnimator(propertyValuesHolder,
             interpolator, startDelay, duration, repeatCount);
     mAnimators.emplace_back(animator);
-    setListener(new PropertyAnimatorSetListener(this));
 
     // Check whether any child animator is infinite after adding it them to the set.
     if (repeatCount == -1) {
@@ -42,6 +41,7 @@ PropertyValuesAnimatorSet::PropertyValuesAnimatorSet()
     setStartValue(0);
     mLastFraction = 0.0f;
     setInterpolator(new LinearInterpolator());
+    setListener(new PropertyAnimatorSetListener(this));
 }
 
 void PropertyValuesAnimatorSet::onFinished(BaseRenderNodeAnimator* animator) {
@@ -115,7 +115,7 @@ void PropertyValuesAnimatorSet::init() {
     std::sort(mAnimators.begin(), mAnimators.end(), [](auto& a, auto&b) {
         return a->getTotalDuration() < b->getTotalDuration();
     });
-    mDuration = mAnimators[mAnimators.size() - 1]->getTotalDuration();
+    mDuration = mAnimators.empty() ? 0 : mAnimators[mAnimators.size() - 1]->getTotalDuration();
     mInitialized = true;
 }