AcceptCriterion (vaadin-all 7.7.46 API)

All Superinterfaces:

Serializable

All Known Implementing Classes:

AbstractSelect.AcceptItem, AbstractSelect.TargetItemIs, AbstractSelect.VerticalLocationIs, AcceptAll, And, ClientSideCriterion, ContainsDataFlavor, Not, Or, ServerSideCriterion, SourceIs, SourceIsTarget, Table.TableDropCriterion, TargetDetailIs, Tree.TargetInSubtree, Tree.TargetItemAllowsChildren, Tree.TreeDropCriterion
```
public interface AcceptCriterion
extends Serializable
```
Criterion that can be used create policy to accept/discard dragged content (presented by Transferable). The drag and drop mechanism will verify the criteria returned by DropHandler.getAcceptCriterion() before calling DropHandler.drop(DragAndDropEvent). The criteria can be evaluated either on the client (browser - see ClientSideCriterion) or on the server (see ServerSideCriterion). If no constraints are needed, an AcceptAll can be used. In addition to accepting or rejecting a possible drop, criteria can provide additional hints for client side painting.

Since:

6.3

See Also:

DropHandler, ClientSideCriterion, ServerSideCriterion

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`accept(DragAndDropEvent dragEvent)`	Validates the data in event to be appropriate for the `DropHandler.drop(DragAndDropEvent)` method.
`boolean`	`isClientSideVerifiable()`	Returns whether the criteria can be checked on the client or whether a server request is needed to check the criteria.
`void`	`paint(PaintTarget target)`
`void`	`paintResponse(PaintTarget target)`	This needs to be implemented iff criterion does some lazy server side initialization.

- Method Detail
  - isClientSideVerifiable
```
boolean isClientSideVerifiable()
```
    Returns whether the criteria can be checked on the client or whether a server request is needed to check the criteria. This requirement may depend on the state of the criterion (e.g. logical operations between criteria), so this cannot be based on a marker interface.
  - paint
```
void paint(PaintTarget target)
    throws PaintException
```
    Throws:
    
    PaintException
  - paintResponse
```
void paintResponse(PaintTarget target)
            throws PaintException
```
    This needs to be implemented iff criterion does some lazy server side initialization. The UIDL painted in this method will be passed to client side drop handler implementation. Implementation can assume that accept(DragAndDropEvent) is called before this method.
    
    Parameters:
    
    target -
    
    Throws:
    
    PaintException
  - accept
```
boolean accept(DragAndDropEvent dragEvent)
```
    Validates the data in event to be appropriate for the DropHandler.drop(DragAndDropEvent) method.
    Note that even if your criterion is validated on client side, you should always validate the data on server side too.
    
    Parameters:
    
    dragEvent -
    
    Returns: