Treeview

A treeview is a graphical user interface control used to present hierarchical data as a tree. Each node may have zero or more child nodes and can typically be expanded or collapsed to show or hide its descendants. Treeviews are common in file managers, integrated development environments, and settings panes.

Data model. A treeview represents a rooted tree where each node contains a label, optional icon, state (expanded or collapsed), and a list of child nodes. Additional per-node metadata may include identifiers, selection state, and optional drag-and-drop handlers. The control supports single or multiple selection and may allow reordering or dragging nodes to reorganize the hierarchy.

Interactions and features. Users expand or collapse nodes via a disclosure control, keyboard or touch gestures. Common features include search or filter, lazy loading of children when a node is expanded, and context menus. Some implementations support drag-and-drop reorganization, inline editing of labels, and multi-column displays.

Implementation and examples. Treeviews exist in many GUI toolkits: Windows TreeView, macOS NSOutlineView, Qt's QTreeView, GtkTreeView, Java Swing JTree, and web-based libraries that render hierarchical lists in HTML. Typical use cases include file explorers, project navigators, and hierarchical settings.

Accessibility and performance. Proper ARIA roles and labeling improve screen reader support in web environments. For large hierarchies, virtualization or virtualization-like techniques reduce rendering costs and memory usage; lazy loading helps when child data is costly to fetch.

Relationship to data structures. A treeview is a user interface representation of a tree data structure. The visual component renders and interacts with the underlying hierarchical data rather than defining the data itself.