Flutter for Beginners

Widget key property

If you take a look at both constructors of statelessWidget and statefulWidget classes, you will notice a parameter named key. This is an important property for widgets in Flutter. It helps in the rendering from the widgets tree to the element tree. Besides the type and a reference to the corresponding widget, this element also holds the key that identifies the widget in the tree. The key property helps to preserve the state of a widget between rebuilds. The most common usage of key is when we are dealing with collections of widgets that have the same type; so, without keys, the element tree would not know which state corresponds to which widget, as they would all have the same type. For example, whenever a widget changes ...