Android: resizing an ImageView in the XML

for example：

<ImageView android:id="@+id/image_view"     
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:adjustViewBounds="true"  
  android:maxWidth="42dp"  
  android:maxHeight="42dp"  
  android:scaleType="fitCenter"  
  android:layout_marginLeft="3dp"  
  android:src="https://stackoverflow.com/questions/6267733/@drawable/icon"  
  /> 

Add property android:scaleType="fitCenter" and android:adjustViewBounds="true".