Android App crashes on animated gradient background

Question

I have added an animated gradient background to my App, but after a few seconds the app crashes. The EXCEPTION says that a linear gradient needs an angle attribute. But there is an angle attribute in every gradient I added to the project. Anybody has a suggestion what I've messed up?

MainActivity.kt

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    //background animation
    val constraintLayout = findViewById<ConstraintLayout>(R.id.layout)
    val animationDrawable = constraintLayout.background as AnimationDrawable
    animationDrawable.setEnterFadeDuration(2000)
    animationDrawable.setExitFadeDuration(4000)
    animationDrawable.start()

...
}

activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/layout"
android:background="@drawable/gradient_list"
tools:context=".MainActivity">
...

gradient_list.xml

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/gradient_1"
    android:duration="5000"/>
<item android:drawable="@drawable/gradient_2"
    android:duration="5000"/>
<item android:drawable="@drawable/gradient_3"
    android:duration="5000"/>
<item android:drawable="@drawable/gradient_4"
    android:duration="5000"/>
</animation-list>

gradient_1.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:angle="225"
    android:endColor="#044fab"
    android:startColor="#f18127"
    android:type="linear"/>
 </shape>

gradient_2.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:angle="45"
    android:endColor="#43b4ef"
    android:startColor="#32ff3f"
    android:type="linear"/>
</shape>

gradient_3.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:angle="70"
    android:endColor="#f674da"
    android:startColor="#38d7bf"
    android:type="linear"/>
</shape>

gradient_4.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:angle="48"
    android:endColor="#e4033e"
    android:startColor="#e6de15"
    android:type="linear"/>
</shape>

Here is the log after the crash:

2021-06-05 23:23:33.409 5892-5892/com.jakobu.memory E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.jakobu.memory, PID: 5892
java.lang.IllegalArgumentException: Linear gradient requires 'angle' attribute to be a multiple of 45
    at android.graphics.drawable.GradientDrawable$GradientState.updateGradientStateOrientation(GradientDrawable.java:2208)
    at android.graphics.drawable.GradientDrawable$GradientState.getOrientation(GradientDrawable.java:2196)
    at android.graphics.drawable.GradientDrawable.ensureValidRect(GradientDrawable.java:1273)
    at android.graphics.drawable.GradientDrawable.draw(GradientDrawable.java:717)
    at android.graphics.drawable.DrawableContainer.draw(DrawableContainer.java:87)
    at android.view.View.getDrawableRenderNode(View.java:21702)
    at android.view.View.drawBackground(View.java:21636)
    at android.view.View.draw(View.java:21413)
    at android.view.View.updateDisplayListIfDirty(View.java:20298)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4372)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4345)
    at android.view.View.updateDisplayListIfDirty(View.java:20258)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4372)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4345)
    at android.view.View.updateDisplayListIfDirty(View.java:20258)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4372)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4345)
    at android.view.View.updateDisplayListIfDirty(View.java:20258)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4372)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4345)
    at android.view.View.updateDisplayListIfDirty(View.java:20258)
    at android.view.ViewGroup.recreateChildDisplayList(ViewGroup.java:4372)
    at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:4345)
    at android.view.View.updateDisplayListIfDirty(View.java:20258)
    at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:575)
    at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:581)
    at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:654)
    at android.view.ViewRootImpl.draw(ViewRootImpl.java:3610)
    at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:3418)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2755)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1721)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7598)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:966)
    at android.view.Choreographer.doCallbacks(Choreographer.java:790)
    at android.view.Choreographer.doFrame(Choreographer.java:725)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:951)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7356)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
    2021-06-05 23:23:33.421 5892-5892/com.jakobu.memory I/Process: Sending signal. PID: 5892 SIG: 9

Answer 1

The problem is in these two files. Gradient angle should be 45 or one of its multiples like 90, 135, 180, 225 ... etc. So change this to 90 gradient_3.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:angle="90"
    android:endColor="#f674da"
    android:startColor="#38d7bf"
    android:type="linear"/>
</shape>

And change this to 45 (the closest to 48) gradient_4.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<gradient
    android:angle="45"
    android:endColor="#e4033e"
    android:startColor="#e6de15"
    android:type="linear"/>
</shape>