我必须为我的 Android Wear 使用 Watchviewstub,这会导致我出现 NullpointerException。当我不使用 WatchviewStub 时,AnimationDrawable 运行良好。
基本上我正在尝试解决它,就像这里描述的那样。阅读这篇文章时我也无法得到答案。
main_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.wearable.view.WatchViewStub
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/too/white"
android:padding="1dp"
android:id="@+id/watch_view_stub"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:rectLayout="@layout/rect_activity_main"
app:roundLayout="@layout/round_activity_main"
tools:context=".MainActivity"
tools:deviceIds="wear">
</android.support.wearable.view.WatchViewStub>
rect_activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:keepScreenOn="true"
android:background="@color/white"
app:layout_box="all"
xmlns:app="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android">
<ImageView
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_marginTop="6dp"
android:layout_marginRight="2dp"
android:id="@+id/heart_animation"
android:layout_gravity="right|top"
android:src="@drawable/heart_animation"/>
<TextView
android:id="@+id/rate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="15sp"
android:text="89"
android:textColor="@color/white"
android:layout_marginTop="10dp"
android:layout_marginRight="13dp"
android:layout_gravity="right|top"/>
</FrameLayout>
可绘制/heart_animation.xml
<?xml version="1.0" encoding="utf-8"?>
<animation-list
android:id="@+id/heart_animation_drawable"
xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false">
<item android:drawable="@drawable/heart_grey" android:duration="500" />
<item android:drawable="@drawable/heart_red" android:duration="900" />
<item android:drawable="@drawable/heart_grey" android:duration="200" />
<item android:drawable="@drawable/heart_red" android:duration="350" />
<item android:drawable="@drawable/heart_grey" android:duration="200" />
<item android:drawable="@drawable/heart_red" android:duration="350" />
</animation-list>
MainActivity.java
ImageView view;
AnimationDrawable frameAnimation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
view = (ImageView) findViewById(R.id.heart_animation);
view.setBackgroundResource(R.drawable.heart_animation);
frameAnimation = (AnimationDrawable) view.getBackground();
}
// Called when Activity becomes visible or invisible to the user
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
if (hasFocus) {
// Starting the animation when in Focus
frameAnimation.start();
} else {
// Stoping the animation when not in Focus
frameAnimation.stop();
}
}
错误:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setBackgroundResource(int)' on a null object reference
at de.denjo.test.MainActivity.onCreate(MainActivity.java:72)