我正在使用此片段开始AnimatedVectorDrawable
动画:
AnimatedVectorDrawable vectorAnim = (AnimatedVectorDrawable) ((ImageView) child).getDrawable();
vectorAnim.start();
(基本上我得到了imageView的android:src
,即AnimatedVectorDrawable
,然后启动动画(。
它在我测试到现在的每个设备上都可以正常工作,但是当我在API 22设备上运行我的应用程序时,我会收到此错误:
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.util.ArrayList.size()' on a null object reference
at android.graphics.drawable.AnimatedVectorDrawable.isStarted(AnimatedVectorDrawable.java:427)
at android.graphics.drawable.AnimatedVectorDrawable.start(AnimatedVectorDrawable.java:440)
at com.brickx.creartup.MainRoadmapAdapter.animateViews(MainRoadmapAdapter.java:263)
at com.brickx.creartup.MainRoadmapAdapter.access$100(MainRoadmapAdapter.java:31)
at com.brickx.creartup.MainRoadmapAdapter$1.onInflate(MainRoadmapAdapter.java:66)
at android.view.ViewStub.inflate(ViewStub.java:284)
at com.brickx.creartup.MainRoadmapAdapter.inflateBackground(MainRoadmapAdapter.java:215)
at com.brickx.creartup.MainRoadmapAdapter.onCreateViewHolder(MainRoadmapAdapter.java:71)
at com.brickx.creartup.MainRoadmapAdapter.onCreateViewHolder(MainRoadmapAdapter.java:31)
at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6519)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5706)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5589)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5585)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2231)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1558)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1518)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:610)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3719)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3436)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3988)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:611)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1076)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1197)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:132)
at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1361)
at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:874)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1172)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
at android.view.View.layout(View.java:15671)
at android.view.ViewGroup.layout(ViewGroup.java:5038)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
at android.view.View.layout(View.java:15671)
对这里发生的事情有任何想法吗?
编辑
我知道NullPointerException
的含义,但可悲的是,我认为我无法控制这一点。而且我不知道为什么在这里抛出这个例外...
好吧,我发现了问题的根!即使我不知道如何正确解决此问题。
当我尝试在没有target
属性的AnimatedVectorDrawable
上启动动画时发生崩溃(我正在使用一个XML文件来定义矢量绘制及其动画(。
更确切地说,我认为Android查看了animated-vector
元素,如果找到target
,则会引发错误。再次,到目前为止,我仅在API 22上遇到了这个问题,但是我还没有测试过其他API ...
我只能想到两个解决方案暂时:
- 在
AnimatedVectorDrawable
中至少添加一个target
元素, - 或使用简单的
VectorDrawable
(如果不需要动画((我使用AnimatedVectorDrawable
,无论我的矢量是否是动画的,以便在我愿意的情况下轻松地添加动画(。
编辑
我找到了一个简单的解决方法,以避免更改所有内容,也许可以帮助他人:我只需要在所有不应该动画的AnimatedVectorDrawable
中添加一个愚蠢的target
。
<target android:name="vector">
<aapt:attr name="android:animation">
<objectAnimator
android:propertyName="alpha"
android:valueTo="1"/>
</aapt:attr>
</target>
这样,AnimatedVectorDrawable
没有任何变化,但是错误没有显示。我不建议这样做,因为它很脏并且可能导致其他问题。
在API 21和22上找到了相同的问题。
帮助我的解决方案是在XML中的objectAnimator
上定义参数android:valueFrom
和android:valueTo
:
<objectAnimator
android:propertyName="fillColor"
android:duration="250"
android:valueFrom="#393749"
android:valueTo="#00000000"
android:valueType="colorType"/>
但是,在上面的API上,它在没有android:valueFrom
的情况下工作(Crazy Droid不会节省我们的时间:(