Interface NamingContainer
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- All Known Implementing Classes:
HtmlDataTable
,HtmlForm
,UIData
,UIForm
,UINamingContainer
public interface NamingContainer
Interface implemented by components that provide a new "namespace" for the ids of their child components.Component ids must be unique between all descendants of a NamingContainer; the JSF library will report a fatal error and refuse to process or render any view where two components in the same NamingContainer have identical id values. However a component that is a descendant of one NamingContainer component is permitted to have the same id as a component that is a descendant of a different NamingContainer component.
Unique component ids are used to:
- generate unique names for HTML form fields, etc
- search for components via UIComponent.findComponent(String expr)
- on re-render after postback, match up component declarations in the view templates with existing components in the restored view tree.
Requiring every component in a large view (which is possibly built by including or composing multiple files together) to have an id which is different from every other id is simply unmanageable; JSF certainly must provide some kind of id namespacing. Therefore this base class is defined, and a few standard JSF components subclass it (in particular, f:subview).
When generating clientId values during rendering, descendants of a NamingContainer instance are allocated a clientId which is their own id prefixed with the clientId of the ancestor NamingContainer, eg "parentId:childId". NamingContainer components can be nested within other NamingContainer components, generating clientIds like "firstId:middleId:leafId".
Not every component is a naming container; that would technically work, but the clientId values generated would quickly grow excessively long.
See the javadoc for this class in the JSF Specification for further details.
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Field Summary
Fields Modifier and Type Field Description static char
SEPARATOR_CHAR
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Field Detail
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SEPARATOR_CHAR
static final char SEPARATOR_CHAR
- See Also:
- Constant Field Values
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