Android-imageView.getDrawable()返回null
我被困在这个看似简单的问题上。我做错了什么Android-imageView.getDrawable()返回null,android,android-imageview,android-drawable,Android,Android Imageview,Android Drawable,我被困在这个看似简单的问题上。我做错了什么 ImageView mImageView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mImageView = (ImageView)findViewB
ImageView mImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mImageView = (ImageView)findViewById(R.id.control);
ClipDrawable drawable = (ClipDrawable)mImageView.getDrawable();
drawable.setLevel(10);
}
应用程序在drawable.setLevel10崩溃,出现NullPointerException drawable为null
以下是我的xml:
circle.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval"
android:innerRadius="50dp"
>
<solid
android:color="#FFAAFF"/>
</shape>
clip.xml
<?xml version="1.0" encoding="utf-8"?>
<clip xmlns:android="http://schemas.android.com/apk/res/android"
android:clipOrientation="horizontal"
android:drawable="@drawable/circle"
android:gravity="clip_horizontal"
/>
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<ImageView
android:id="@+id/image"
android:layout_height="100dp"
android:layout_width="100dp"
android:background="@drawable/clip"
android:layout_centerHorizontal="true"
/>
</RelativeLayout>
请帮帮我 您设置了'src'的drawable to background属性
android:background=@drawable/clip
。因此,通过将background属性替换为src来更改您的activity_main.xml:
android:src=@drawable/clip
最后,您的活动_main.xml将是:
或者,您可以通过调用getBackground方法来获取drawable,该方法返回由属性android:background设置的drawable
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<ImageView
android:id="@+id/image"
android:layout_height="100dp"
android:layout_width="100dp"
android:scr="@drawable/clip"
android:layout_centerHorizontal="true"
/>