Data binding allows easy linking of UI elements and models so that users can edit or view the data in the model. Traditionally, this is what you need to do to link, say, a text widget to a String property of a model object:
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Copy the current value of the model property to the text widget.
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Register listeners with the widget and the model object to propagate changes made on one side to the other side.
The same basic principle applies to binding a list widget’s contents to a collection property of a model object.
Using the data binding framework relieves you from writing and registering listeners yourself, and provides a common infrastructure for validation and conversion. It makes it easy to connect data sources to widgets such as text fields, combos, tables and trees, for viewing and editing. In real life scenarios, changes on one side are not always propagated to the other side right away - changes need to be validated, values converted, and different update policies followed. The data binding framework covers these more advanced aspects as well.