Class DocumentFilter

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.

Since:
1.4
See Also:
Document, AbstractDocument, DefaultStyledDocument

Nested Classes

Modifier and Type Class Description
static class  DocumentFilter.FilterBypass

Used as a way to circumvent calling back into the Document to change it.

Constructors

Constructor Description
DocumentFilter()

Methods

Modifier and Type Method Description
void insertString​(DocumentFilter.FilterBypass fb, int offset, String string, AttributeSet attr)

Invoked prior to insertion of text into the specified Document.
void remove​(DocumentFilter.FilterBypass fb, int offset, int length)

Invoked prior to removal of the specified region in the specified Document.
void replace​(DocumentFilter.FilterBypass fb, int offset, int length, String text, AttributeSet attrs)

Invoked prior to replacing a region of text in the specified Document.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructors

DocumentFilter

public DocumentFilter()

Methods

remove

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.

Parameters:
fb - FilterBypass that can be used to mutate Document
offset - the offset from the beginning >= 0
length - the number of characters to remove >= 0
Throws:
BadLocationException - 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.

insertString

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.

Parameters:
fb - FilterBypass that can be used to mutate Document
offset - 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 insert
attr - the attributes to associate with the inserted content. This may be null if there are no attributes.
Throws:
BadLocationException - the given insert position is not a valid position within the document

replace

public 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.

Parameters:
fb - FilterBypass that can be used to mutate Document
offset - Location in Document
length - Length of text to delete
text - Text to insert, null indicates no text to insert
attrs - AttributeSet indicating attributes of inserted text, null is legal.
Throws:
BadLocationException - the given insert position is not a valid position within the document

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https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/javax/swing/text/DocumentFilter.html