AppBar({Key key, Widget leading, Widget title, List<Widget> actions, Widget flexibleSpace, AppBarBottomWidget bottom, int elevation: 4, Color backgroundColor, Brightness brightness, IconThemeData iconTheme, TextTheme textTheme, EdgeInsets padding: EdgeInsets.zero, bool centerTitle, Object heroTag, double expandedHeight, double collapsedHeight })

Creates a material design app bar.

Typically used in the appBar property.

Source 

AppBar({
  Key key,
  this.leading,
  this.title,
  this.actions,
  this.flexibleSpace,
  this.bottom,
  this.elevation: 4,
  this.backgroundColor,
  this.brightness,
  this.iconTheme,
  this.textTheme,
  this.padding: EdgeInsets.zero,
  this.centerTitle,
  this.heroTag,
  double expandedHeight,
  double collapsedHeight
}) : _expandedHeight = expandedHeight,
     _collapsedHeight = collapsedHeight,
     super(key: key);