public class DocumentFilter extends Object
DocumentFilter, as the name implies, is a filter for the Document mutation methods. When a Document containing a DocumentFilter is modified (either through insert or remove), it forwards the appropriate method invocation to the DocumentFilter. The default implementation allows the modification to occur. Subclasses can filter the modifications by conditionally invoking methods on the superclass, or invoking the necessary methods on the passed in FilterBypass. Subclasses should NOT call back into the Document for the modification instead call into the superclass or the FilterBypass.
When remove or insertString is invoked on the DocumentFilter, the DocumentFilter may callback into the FilterBypass multiple times, or for different regions, but it should not callback into the FilterBypass after returning from the remove or insertString method.
By default, text related document mutation methods such as insertString, replace and remove in AbstractDocument use DocumentFilter when available, and Element related mutation methods such as create, insert and removeElement in DefaultStyledDocument do not use DocumentFilter. If a method doesn't follow these defaults, this must be explicitly stated in the method documentation.
Document, AbstractDocument, DefaultStyledDocument
| Modifier and Type | Class and Description |
|---|---|
static class |
DocumentFilter.FilterBypass Used as a way to circumvent calling back into the Document to change it. |
public DocumentFilter()
public void remove(DocumentFilter.FilterBypass fb,
int offset,
int length)
throws BadLocationException Invoked prior to removal of the specified region in the specified Document. Subclasses that want to conditionally allow removal should override this and only call supers implementation as necessary, or call directly into the FilterBypass as necessary.
fb - FilterBypass that can be used to mutate Documentoffset - the offset from the beginning >= 0length - the number of characters to remove >= 0BadLocationException - some portion of the removal range was not a valid part of the document. The location in the exception is the first bad position encountered.public void insertString(DocumentFilter.FilterBypass fb,
int offset,
String string,
AttributeSet attr)
throws BadLocationException Invoked prior to insertion of text into the specified Document. Subclasses that want to conditionally allow insertion should override this and only call supers implementation as necessary, or call directly into the FilterBypass.
fb - FilterBypass that can be used to mutate Documentoffset - the offset into the document to insert the content >= 0. All positions that track change at or after the given location will move.string - the string to insertattr - the attributes to associate with the inserted content. This may be null if there are no attributes.BadLocationException - the given insert position is not a valid position within the documentpublic void replace(DocumentFilter.FilterBypass fb,
int offset,
int length,
String text,
AttributeSet attrs)
throws BadLocationException Invoked prior to replacing a region of text in the specified Document. Subclasses that want to conditionally allow replace should override this and only call supers implementation as necessary, or call directly into the FilterBypass.
fb - FilterBypass that can be used to mutate Documentoffset - Location in Documentlength - Length of text to deletetext - Text to insert, null indicates no text to insertattrs - AttributeSet indicating attributes of inserted text, null is legal.BadLocationException - the given insert position is not a valid position within the document
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