javax.swing.text

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

    • Constructor Detail

      • DocumentFilter

        public DocumentFilter()

    • Method Detail

      • 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