TabBar({Key key, @required Map<T, TabLabel> labels, bool isScrollable: false, Color indicatorColor, Color labelColor })

Creates a widget that displays a horizontal row of tabs, one per label.

The labels argument must not be null.

Source 

TabBar({
  Key key,
  @required this.labels,
  this.isScrollable: false,
  this.indicatorColor,
  this.labelColor
}) : super(key: key, scrollDirection: Axis.horizontal) {
  assert(labels != null);
}