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## javax.faces.component.visit
Class VisitContext

    java.lang.Object
      javax.faces.component.visit.VisitContext

Direct Known Subclasses:
  VisitContextWrapper

    public abstract class VisitContext

extends Object

A context object that is used to hold state relating to performing a component tree visit.

Component tree visits are initiated by calling `UIComponent.visitTree(javax.faces.component.visit.VisitContext, javax.faces.component.visit.VisitCallback)`, at which point both a `VisitContext` and a `VisitCallback` must be provided.

Since:
  2.0
See Also:
  `UIComponent.visitTree()`, `VisitCallback`

Field Summary
`static Collection<String>` | `ALL_IDS` This unmodifiable Collection is returned by `getIdsToVisit()` and `getSubtreeIdsToVisit()` in cases where all ids should be visited.

Constructor Summary
`VisitContext()`

Method Summary
`static VisitContext` | `createVisitContext(FacesContext context)` Creates a VisitContext instance for use with `UIComponent.visitTree()`.
`static VisitContext` | `createVisitContext(FacesContext context, Collection<String> ids, Set<VisitHint> hints)` Returns a VisitContext instance that is initialized with the specified ids and hintsfor use with `UIComponent.visitTree(javax.faces.component.visit.VisitContext, javax.faces.component.visit.VisitCallback)`.
`abstract FacesContext` | `getFacesContext()` Returns the FacesContext for the current request.
`abstract Set<VisitHint>` | `getHints()` Returns hints that influence the behavior of the tree visit.
`abstract Collection<String>` | `getIdsToVisit()` Returns the ids of the components to visit.
`abstract Collection<String>` | `getSubtreeIdsToVisit(UIComponent component)` Given a `NamingContainer` component, returns the client ids of any components underneath the NamingContainer that should be visited.
`abstract VisitResult` | `invokeVisitCallback(UIComponent component, VisitCallback callback)` Called by `UIComponent.visitTree()` to visit a single component.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### ALL_IDS

    public static final Collection<String> ALL_IDS

  This unmodifiable Collection is returned by `getIdsToVisit()` and `getSubtreeIdsToVisit()` in cases where all ids should be visited.

  To simplify logic for `visitTree()` implementations, this Collection always returns `false` for `isEmpty`. All other methods throw `UnsupportedOperationException`.

  Since:
    2.0

Constructor Detail

### VisitContext

    public VisitContext()

Method Detail

### getFacesContext

    public abstract FacesContext getFacesContext()

  Returns the FacesContext for the current request.

  Since:
    2.0

### getIdsToVisit

    public abstract Collection<String> getIdsToVisit()

  Returns the ids of the components to visit.

  In the case of a full tree visit, this method returns the ALL_IDS collection. Otherwise, if a partial visit is beign performed, returns a modifiable collection containing the client ids of the components that should be visited.

### getSubtreeIdsToVisit

    public abstract Collection<String> getSubtreeIdsToVisit(UIComponent component)

  Given a `NamingContainer` component, returns the client ids of any components underneath the NamingContainer that should be visited.

  This method is called by NamingContainer visitTree() implementations to determine whether the NamingContainer contains components to be visited. In the case where no such components exist, the NamingContainer can short-circuit the tree visit and avoid descending into child subtrees.

  In addition, iterating components such as UIData may be able to use the returned ids to determine which iterated states (ie. rows) need to be visited. This allows the visit traversal to be contstrained such only those rows that contain visit targets need to be traversed.

  Parameters:
    `component` - a NamingContainer component
  Returns:
    an unmodifiable Collection containing the client ids of any components underneath the NamingContainer that are known to be targets of the tree visit. If no such components exist, returns an empty Collection. If all components underneath the NamingContainer should be visited, returns the `VisitContext.ALL_IDS` collection.
  Throws:
    `IllegalArgumentException` - if `component` is not an instance of NamingContainer

### invokeVisitCallback

    public abstract VisitResult invokeVisitCallback(UIComponent component,
                                                    VisitCallback callback)

  Called by `UIComponent.visitTree()` to visit a single component.

  Parameters:
    `component` - the component to visit
    `callback` - the VisitCallback to call
  Returns:
    a VisitResult value that indicates whether to continue visiting the component's subtree, skip visiting the component's subtree or abort the visit altogether.

### getHints

    public abstract Set<VisitHint> getHints()

  Returns hints that influence the behavior of the tree visit.

  Interested parties, such as `UIComponent.visitTree()` implementations, may check to see whether a particular hint is present by calling `VisitContext.getHints().contains()`, passing in one of the hints defined by `VisitHint`.

  Returns:
    a non-empty, unmodifiable collection of VisitHints

### createVisitContext

    public static VisitContext createVisitContext(FacesContext context,
                                                  Collection<String> ids,
                                                  Set<VisitHint> hints)

  Returns a VisitContext instance that is initialized with the specified ids and hintsfor use with `UIComponent.visitTree(javax.faces.component.visit.VisitContext, javax.faces.component.visit.VisitCallback)`.

  Parameters:
    `context` - the FacesContext for the current request
    `ids` - the client ids of the components to visit. If null, all components will be visited.
    `hints` - the VisitHints to apply to the visit. If `null`, no hints are applied.
  Returns:
    a VisitContext instance that is initialized with the specified ids and hints.

### createVisitContext

    public static VisitContext createVisitContext(FacesContext context)

  Creates a VisitContext instance for use with `UIComponent.visitTree()`. This method can be used to obtain a VisitContext instance when all components should be visited with the default visit hints.

  Parameters:
    `context` - the FacesContext for the current request
  Returns:
    a VisitContext instance

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