This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


javax.swing.text
class AbstractDocument

java.lang.Object extended by javax.swing.text.AbstractDocument
All Implemented Interfaces:
Serializable, Document
Direct Known Subclasses:
DefaultStyledDocument, PlainDocument

public abstract class AbstractDocument
extends Object
implements Document, Serializable

An implementation of the document interface to serve as a basis for implementing various kinds of documents. At this level there is very little policy, so there is a corresponding increase in difficulty of use.

This class implements a locking mechanism for the document. It allows multiple readers or one writer, and writers must wait until all observers of the document have been notified of a previous change before beginning another mutation to the document. The read lock is acquired and released using the render method. A write lock is aquired by the methods that mutate the document, and are held for the duration of the method call. Notification is done on the thread that produced the mutation, and the thread has full read access to the document for the duration of the notification, but other readers are kept out until the notification has finished. The notification is a beans event notification which does not allow any further mutations until all listeners have been notified.

Any models subclassed from this class and used in conjunction with a text component that has a look and feel implementation that is derived from BasicTextUI may be safely updated asynchronously, because all access to the View hierarchy is serialized by BasicTextUI if the document is of type AbstractDocument. The locking assumes that an independent thread will access the View hierarchy only from the DocumentListener methods, and that there will be only one event thread active at a time.

If concurrency support is desired, there are the following additional implications. The code path for any DocumentListener implementation and any UndoListener implementation must be threadsafe, and not access the component lock if trying to be safe from deadlocks. The repaint and revalidate methods on JComponent are safe.

AbstractDocument models an implied break at the end of the document. Among other things this allows you to position the caret after the last character. As a result of this, getLength returns one less than the length of the Content. If you create your own Content, be sure and initialize it to have an additional character. Refer to StringContent and GapContent for examples of this. Another implication of this is that Elements that model the implied end character will have an endOffset == (getLength() + 1). For example, in DefaultStyledDocument getParagraphElement(getLength()).getEndOffset() == getLength() + 1 .

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeansTM has been added to the java.beans package. Please see {@link java.beans.XMLEncoder}.


Nested Class Summary
abstract class

           Implements the abstract part of an element.
static interface

           An interface that can be used to allow MutableAttributeSet implementations to use pluggable attribute compression techniques.
 class

           Implements a composite element that contains other elements.
static interface

           Interface to describe a sequence of character content that can be edited.
 class

           Stores document changes as the document is being modified.
static class

           An implementation of ElementChange that can be added to the document event.
 class

           Implements an element that directly represents content of some kind.
 
Field Summary
protected static String BAD_LOCATION
          Error message to indicate a bad location.
static String BidiElementName
          Name of elements used to hold a unidirectional run
static String ContentElementName
          Name of elements used to represent content
static String ElementNameAttribute
          Name of the attribute used to specify element names.
protected EventListenerList listenerList
          The event listener list for the document.
static String ParagraphElementName
          Name of elements used to represent paragraphs
static String SectionElementName
          Name of elements used to hold sections (lines/paragraphs).
 
Constructor Summary
protected

          Constructs a new AbstractDocument, wrapped around some specified content storage mechanism.
protected

          Constructs a new AbstractDocument, wrapped around some specified content storage mechanism.
 
Method Summary
 void

          Adds a document listener for notification of any changes.
 void

          Adds an undo listener for notification of any changes.
protected Element

          Creates a document branch element, that can contain other elements.
protected Element
createLeafElement(Element parent, AttributeSet a, int p0, int p1)

          Creates a document leaf element.
 Position
createPosition(int offs)

          Returns a position that will track change as the document is altered.
 void

          Gives a diagnostic dump.
protected void

          Notifies all listeners that have registered interest for notification on this event type.
protected void

          Notifies all listeners that have registered interest for notification on this event type.
protected void

          Notifies all listeners that have registered interest for notification on this event type.
protected void

          Notifies all listeners that have registered interest for notification on this event type.
 int

          Gets the asynchronous loading priority.
protected AbstractDocument.AttributeContext

          Fetches the context for managing attributes.
 Element

          Returns the root element of the bidirectional structure for this document.
protected AbstractDocument.Content

          Gets the content for the document.
protected Thread

          Fetches the current writing thread if there is one.
abstract Element

          Returns the root element that views should be based upon unless some other mechanism for assigning views to element structures is provided.
 DocumentFilter

          Returns the DocumentFilter that is responsible for filtering of insertion/removal.
 DocumentListener[]

          Returns an array of all the document listeners registered on this document.
 Dictionary

          Supports managing a set of properties.
 Position

          Returns a position that represents the end of the document.
 int

          Returns the length of the data.
 EventListener[]
getListeners(Class listenerType)

          Returns an array of all the objects currently registered as FooListeners upon this document.
abstract Element

          Get the paragraph element containing the given position.
 Object

          A convenience method for looking up a property value.
 Element[]

          Gets all root elements defined.
 Position

          Returns a position that represents the start of the document.
 String
getText(int offset, int length)

          Gets a sequence of text from the document.
 void
getText(int offset, int length, Segment txt)

          Fetches the text contained within the given portion of the document.
 UndoableEditListener[]

          Returns an array of all the undoable edit listeners registered on this document.
 void
insertString(int offs, String str, AttributeSet a)

          Inserts some content into the document.
protected void

          Updates document structure as a result of text insertion.
protected void

          Updates any document structure as a result of text removal.
 void
putProperty(Object key, Object value)

          A convenience method for storing up a property value.
 void

          Acquires a lock to begin reading some state from the document.
 void

          Does a read unlock.
 void
remove(int offs, int len)

          Removes some content from the document.
 void

          Removes a document listener.
 void

          Removes an undo listener.
protected void

          Updates any document structure as a result of text removal.
 void

          This allows the model to be safely rendered in the presence of currency, if the model supports being updated asynchronously.
 void
replace(int offset, int length, String text, AttributeSet attrs)

          Deletes the region of text from offset to offset + length, and replaces it with text.
 void

          Sets the asynchronous loading priority.
 void

          Sets the DocumentFilter.
 void

          Replaces the document properties dictionary for this document.
protected void

          Acquires a lock to begin mutating the document this lock protects.
protected void

          Releases a write lock previously obtained via writeLock.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

BAD_LOCATION

protected static final String BAD_LOCATION
Error message to indicate a bad location.

BidiElementName

public static final String BidiElementName
Name of elements used to hold a unidirectional run

ContentElementName

public static final String ContentElementName
Name of elements used to represent content

ElementNameAttribute

public static final String ElementNameAttribute
Name of the attribute used to specify element names.

listenerList

protected EventListenerList listenerList
The event listener list for the document.

ParagraphElementName

public static final String ParagraphElementName
Name of elements used to represent paragraphs

SectionElementName

public static final String SectionElementName
Name of elements used to hold sections (lines/paragraphs).
Constructor Detail

AbstractDocument

protected AbstractDocument(AbstractDocument.Content data)
Constructs a new AbstractDocument, wrapped around some specified content storage mechanism.

Parameters:
data - the content

AbstractDocument

protected AbstractDocument(AbstractDocument.Content data,
                           AbstractDocument.AttributeContext context)
Constructs a new AbstractDocument, wrapped around some specified content storage mechanism.

Parameters:
data - the content
context - the attribute context
Method Detail

addDocumentListener

public void addDocumentListener(DocumentListener listener)
Adds a document listener for notification of any changes.

Parameters:
listener - the DocumentListener to add

addUndoableEditListener

public void addUndoableEditListener(UndoableEditListener listener)
Adds an undo listener for notification of any changes. Undo/Redo operations performed on the UndoableEdit will cause the appropriate DocumentEvent to be fired to keep the view(s) in sync with the model.

Parameters:
listener - the UndoableEditListener to add

createBranchElement

protected Element createBranchElement(Element parent,
                                      AttributeSet a)
Creates a document branch element, that can contain other elements.

Parameters:
parent - the parent element
a - the attributes
Returns:
the element

createLeafElement

protected Element createLeafElement(Element parent,
                                    AttributeSet a,
                                    int p0,
                                    int p1)
Creates a document leaf element. Hook through which elements are created to represent the document structure. Because this implementation keeps structure and content separate, elements grow automatically when content is extended so splits of existing elements follow. The document itself gets to decide how to generate elements to give flexibility in the type of elements used.

Parameters:
parent - the parent element
a - the attributes for the element
p0 - the beginning of the range >= 0
p1 - the end of the range >= p0
Returns:
the new element

createPosition

public synchronized Position createPosition(int offs)
                                     throws BadLocationException
Returns a position that will track change as the document is altered.

This method is thread safe, although most Swing methods are not. Please see How to Use Threads for more information.

Parameters:
offs - the position in the model >= 0
Returns:
the position
Throws:
BadLocationException - if the given position does not represent a valid location in the associated document

dump

public void dump(PrintStream out)
Gives a diagnostic dump.

Parameters:
out - the output stream

fireChangedUpdate

protected void fireChangedUpdate(DocumentEvent e)
Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created using the parameters passed into the fire method.

Parameters:
e - the event

fireInsertUpdate

protected void fireInsertUpdate(DocumentEvent e)
Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created using the parameters passed into the fire method.

Parameters:
e - the event

fireRemoveUpdate

protected void fireRemoveUpdate(DocumentEvent e)
Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created using the parameters passed into the fire method.

Parameters:
e - the event

fireUndoableEditUpdate

protected void fireUndoableEditUpdate(UndoableEditEvent e)
Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created using the parameters passed into the fire method.

Parameters:
e - the event

getAsynchronousLoadPriority

public int getAsynchronousLoadPriority()
Gets the asynchronous loading priority. If less than zero, the document should not be loaded asynchronously.

Returns:
the asynchronous loading priority, or -1 if the document should not be loaded asynchronously

getAttributeContext

protected final AbstractDocument.AttributeContext getAttributeContext()
Fetches the context for managing attributes. This method effectively establishes the strategy used for compressing AttributeSet information.

Returns:
the context

getBidiRootElement

public Element getBidiRootElement()
Returns the root element of the bidirectional structure for this document. Its children represent character runs with a given Unicode bidi level.


getContent

protected final AbstractDocument.Content getContent()
Gets the content for the document.

Returns:
the content

getCurrentWriter

protected final synchronized Thread getCurrentWriter()
Fetches the current writing thread if there is one. This can be used to distinguish whether a method is being called as part of an existing modification or if a lock needs to be acquired and a new transaction started.

Returns:
the thread actively modifying the document or null if there are no modifications in progress

getDefaultRootElement

public abstract Element getDefaultRootElement()
Returns the root element that views should be based upon unless some other mechanism for assigning views to element structures is provided.

Returns:
the root element

getDocumentFilter

public DocumentFilter getDocumentFilter()
Returns the DocumentFilter that is responsible for filtering of insertion/removal. A null return value implies no filtering is to occur.

Returns:
the DocumentFilter

getDocumentListeners

public DocumentListener[] getDocumentListeners()
Returns an array of all the document listeners registered on this document.

Returns:
all of this document's DocumentListeners or an empty array if no document listeners are currently registered

getDocumentProperties

public Dictionary getDocumentProperties()
Supports managing a set of properties. Callers can use the documentProperties dictionary to annotate the document with document-wide properties.

Returns:
a non-null Dictionary

getEndPosition

public final Position getEndPosition()
Returns a position that represents the end of the document. The position returned can be counted on to track change and stay located at the end of the document.

Returns:
the position

getLength

public int getLength()
Returns the length of the data. This is the number of characters of content that represents the users data.

Returns:
the length >= 0

getListeners

public EventListener[] getListeners(Class listenerType)
Returns an array of all the objects currently registered as FooListeners upon this document. FooListeners are registered using the addFooListener method.

You can specify the listenerType argument with a class literal, such as FooListener.class. For example, you can query a document d for its document listeners with the following code:

DocumentListener[] mls = (DocumentListener[])(d.getListeners(DocumentListener.class));
If no such listeners exist, this method returns an empty array.

Parameters:
listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
Returns:
an array of all objects registered as FooListeners on this component, or an empty array if no such listeners have been added

getParagraphElement

public abstract Element getParagraphElement(int pos)
Get the paragraph element containing the given position. Sub-classes must define for themselves what exactly constitutes a paragraph. They should keep in mind however that a paragraph should at least be the unit of text over which to run the Unicode bidirectional algorithm.

Parameters:
pos - the starting offset >= 0
Returns:
the element

getProperty

public final Object getProperty(Object key)
A convenience method for looking up a property value. It is equivalent to:
 getDocumentProperties().get(key);
 

Parameters:
key - the non-null property key
Returns:
the value of this property or null

getRootElements

public Element[] getRootElements()
Gets all root elements defined. Typically, there will only be one so the default implementation is to return the default root element.

Returns:
the root element

getStartPosition

public final Position getStartPosition()
Returns a position that represents the start of the document. The position returned can be counted on to track change and stay located at the beginning of the document.

Returns:
the position

getText

public String getText(int offset,
                      int length)
               throws BadLocationException
Gets a sequence of text from the document.

Parameters:
offset - the starting offset >= 0
length - the number of characters to retrieve >= 0
Returns:
the text
Throws:
BadLocationException - the range given includes a position that is not a valid position within the document

getText

public void getText(int offset,
                    int length,
                    Segment txt)
             throws BadLocationException
Fetches the text contained within the given portion of the document.

If the partialReturn property on the txt parameter is false, the data returned in the Segment will be the entire length requested and may or may not be a copy depending upon how the data was stored. If the partialReturn property is true, only the amount of text that can be returned without creating a copy is returned. Using partial returns will give better performance for situations where large parts of the document are being scanned. The following is an example of using the partial return to access the entire document:

   int nleft = doc.getDocumentLength();
   Segment text = new Segment();
   int offs = 0;
   text.setPartialReturn(true);   
   while (nleft > 0) {
       doc.getText(offs, nleft, text);
       // do something with text
       nleft -= text.count;
       offs += text.count;
   }
 

Parameters:
offset - the starting offset >= 0
length - the number of characters to retrieve >= 0
txt - the Segment object to retrieve the text into
Throws:
BadLocationException - the range given includes a position that is not a valid position within the document

getUndoableEditListeners

public UndoableEditListener[] getUndoableEditListeners()
Returns an array of all the undoable edit listeners registered on this document.

Returns:
all of this document's UndoableEditListeners or an empty array if no undoable edit listeners are currently registered

insertString

public void insertString(int offs,
                         String str,
                         AttributeSet a)
                  throws BadLocationException
Inserts some content into the document. Inserting content causes a write lock to be held while the actual changes are taking place, followed by notification to the observers on the thread that grabbed the write lock.

This method is thread safe, although most Swing methods are not. Please see How to Use Threads for more information.

Parameters:
offs - the starting offset >= 0
str - the string to insert; does nothing with null/empty strings
a - the attributes for the inserted content
Throws:
BadLocationException - the given insert position is not a valid position within the document

insertUpdate

protected void insertUpdate(AbstractDocument.DefaultDocumentEvent chng,
                            AttributeSet attr)
Updates document structure as a result of text insertion. This will happen within a write lock. If a subclass of this class reimplements this method, it should delegate to the superclass as well.

Parameters:
chng - a description of the change
attr - the attributes for the change

postRemoveUpdate

protected void postRemoveUpdate(AbstractDocument.DefaultDocumentEvent chng)
Updates any document structure as a result of text removal. This method is called after the text has been removed from the Content. This will happen within a write lock. If a subclass of this class reimplements this method, it should delegate to the superclass as well.

Parameters:
chng - a description of the change

putProperty

public final void putProperty(Object key,
                              Object value)
A convenience method for storing up a property value. It is equivalent to:
 getDocumentProperties().put(key, value);
 
If value is null this method will remove the property.

Parameters:
key - the non-null key
value - the property value

readLock

public final synchronized void readLock()
Acquires a lock to begin reading some state from the document. There can be multiple readers at the same time. Writing blocks the readers until notification of the change to the listeners has been completed. This method should be used very carefully to avoid unintended compromise of the document. It should always be balanced with a readUnlock.


readUnlock

public final synchronized void readUnlock()
Does a read unlock. This signals that one of the readers is done. If there are no more readers then writing can begin again. This should be balanced with a readLock, and should occur in a finally statement so that the balance is guaranteed. The following is an example.

     readLock();
     try {
         // do something
     } finally {
         readUnlock();
     }
 


remove

public void remove(int offs,
                   int len)
            throws BadLocationException
Removes some content from the document. Removing content causes a write lock to be held while the actual changes are taking place. Observers are notified of the change on the thread that called this method.

This method is thread safe, although most Swing methods are not. Please see How to Use Threads for more information.

Parameters:
offs - the starting offset >= 0
len - the number of characters to remove >= 0
Throws:
BadLocationException - the given remove position is not a valid position within the document

removeDocumentListener

public void removeDocumentListener(DocumentListener listener)
Removes a document listener.

Parameters:
listener - the DocumentListener to remove

removeUndoableEditListener

public void removeUndoableEditListener(UndoableEditListener listener)
Removes an undo listener.

Parameters:
listener - the UndoableEditListener to remove

removeUpdate

protected void removeUpdate(AbstractDocument.DefaultDocumentEvent chng)
Updates any document structure as a result of text removal. This method is called before the text is actually removed from the Content. This will happen within a write lock. If a subclass of this class reimplements this method, it should delegate to the superclass as well.

Parameters:
chng - a description of the change

render

public void render(Runnable r)
This allows the model to be safely rendered in the presence of currency, if the model supports being updated asynchronously. The given runnable will be executed in a way that allows it to safely read the model with no changes while the runnable is being executed. The runnable itself may not make any mutations.

This is implemented to aquire a read lock for the duration of the runnables execution. There may be multiple runnables executing at the same time, and all writers will be blocked while there are active rendering runnables. If the runnable throws an exception, its lock will be safely released. There is no protection against a runnable that never exits, which will effectively leave the document locked for it's lifetime.

If the given runnable attempts to make any mutations in this implementation, a deadlock will occur. There is no tracking of individual rendering threads to enable detecting this situation, but a subclass could incur the overhead of tracking them and throwing an error.

This method is thread safe, although most Swing methods are not. Please see How to Use Threads for more information.

Parameters:
r - the renderer to execute

replace

public void replace(int offset,
                    int length,
                    String text,
                    AttributeSet attrs)
             throws BadLocationException
Deletes the region of text from offset to offset + length, and replaces it with text. It is up to the implementation as to how this is implemented, some implementations may treat this as two distinct operations: a remove followed by an insert, others may treat the replace as one atomic operation.

Parameters:
offset - index of child element
length - length of text to delete, may be 0 indicating don't delete anything
text - text to insert, null indicates no text to insert
attrs - AttributeSet indicating attributes of inserted text, null is legal, and typically treated as an empty attributeset, but exact interpretation is left to the subclass
Throws:
BadLocationException - the given position is not a valid position within the document

setAsynchronousLoadPriority

public void setAsynchronousLoadPriority(int p)
Sets the asynchronous loading priority.

Parameters:
p - the new asynchronous loading priority; a value less than zero indicates that the document should not be loaded asynchronously

setDocumentFilter

public void setDocumentFilter(DocumentFilter filter)
Sets the DocumentFilter. The DocumentFilter is passed insert and remove to conditionally allow inserting/deleting of the text. A null value indicates that no filtering will occur.

Parameters:
filter - the DocumentFilter used to constrain text

setDocumentProperties

public void setDocumentProperties(Dictionary x)
Replaces the document properties dictionary for this document.

Parameters:
x - the new dictionary

writeLock

protected final synchronized void writeLock()
Acquires a lock to begin mutating the document this lock protects. There can be no writing, notification of changes, or reading going on in order to gain the lock. Additionally a thread is allowed to gain more than one writeLock, as long as it doesn't attempt to gain additional writeLocks from within document notification. Attempting to gain a writeLock from within a DocumentListener notification will result in an IllegalStateException. The ability to obtain more than one writeLock per thread allows subclasses to gain a writeLock, perform a number of operations, then release the lock.

Calls to writeLock must be balanced with calls to writeUnlock, else the Document will be left in a locked state so that no reading or writing can be done.


writeUnlock

protected final synchronized void writeUnlock()
Releases a write lock previously obtained via writeLock. After decrementing the lock count if there are no oustanding locks this will allow a new writer, or readers.



This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.