为什么自定义ImageView会导致应用程序崩溃

Question

我有一个自定义的ImageView类，我遵循了所有讨论here。但我的应用程序仍然崩溃。我的班级是

  public class DrawView extends ImageView  {        

        public DrawView(Context context) {
            super(context);
        }

        public DrawView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        public DrawView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }

        @Override
        public void onDraw(Canvas canvas) {
            super.onDraw(canvas);

            Paint paint = new Paint();
            paint.setColor(getResources().getColor(R.color.lime));
            paint.setStyle(Paint.Style.FILL_AND_STROKE);
            paint.setStrokeWidth(3);
            canvas.drawRect(touchCornerList.get(0), touchCornerList.get(1), 
                    touchCornerList.get(2), touchCornerList.get(3), paint);
            touchCornerList.clear();

        }

    }

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" 
    android:focusable="true" >

    <DrawView
    android:id="@+id/mainImageView"       
    android:layout_centerInParent="true"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_marginLeft="0dp"
    android:layout_marginRight="0dp"  
    android:layout_marginBottom="10dp"
    android:layout_above="@+id/ImageCaptureButton"
    android:contentDescription="@string/mainview_description"
    /> 
</RelativeLayout>

LogCast消息是应用程序无法启动，因为DrawView xml。我的DrawView有什么问题。 该应用程序在setContentView(R.layout.activity_main); MainActivity's onCreate()处崩溃。 感谢。