DocumentEvent (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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Java^TM 2 Platform
Std. Ed. v1.4.1

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javax.swing.event
Interface DocumentEvent

All Known Implementing Classes:: AbstractDocument.DefaultDocumentEvent

public interface DocumentEvent

Interface for document change notifications. This provides detailed information to Document observers about how the Document changed. It provides high level information such as type of change and where it occurred, as well as the more detailed structural changes (What Elements were inserted and removed).

See Also:: Document, DocumentListener

Nested Class Summary

static interface DocumentEvent.ElementChange
          Describes changes made to a specific element.

static class DocumentEvent.EventType
          Enumeration for document event types

Method Summary

DocumentEvent.ElementChange getChange(Element elem)
          Gets the change information for the given element.

Document getDocument()
          Gets the document that sourced the change event.

int getLength()
          Returns the length of the change.

int getOffset()
          Returns the offset within the document of the start of the change.

DocumentEvent.EventType getType()
          Gets the type of event.

Method Detail

getOffset

public int getOffset()

Returns the offset within the document of the start of the change.

Returns:: the offset >= 0

getLength

public int getLength()

Returns the length of the change.

Returns:: the length >= 0

getDocument

public Document getDocument()

Gets the document that sourced the change event.

Returns:: the document

getType

public DocumentEvent.EventType getType()

Gets the type of event.

Returns:: the type

getChange

public DocumentEvent.ElementChange getChange(Element elem)

Gets the change information for the given element. The change information describes what elements were added and removed and the location. If there were no changes, null is returned.

This method is for observers to discover the structural changes that were made. This means that only elements that existed prior to the mutation (and still exist after the mutatino) need to have ElementChange records. The changes made available need not be recursive.

For example, if the an element is removed from it's parent, this method should report that the parent changed and provide an ElementChange implementation that describes the change to the parent. If the child element removed had children, these elements do not need to be reported as removed.

If an child element is insert into a parent element, the parent element should report a change. If the child element also had elements inserted into it (grandchildren to the parent) these elements need not report change.

Parameters:: elem - the element
Returns:: the change information, or null if the element was not modified