- java.lang.Object
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- javax.swing.text.GapContent
 
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- All Implemented Interfaces:
- Serializable,- AbstractDocument.Content
 
 public class GapContent extends Object implements AbstractDocument.Content, Serializable An implementation of the AbstractDocument.Content interface implemented using a gapped buffer similar to that used by emacs. The underlying storage is a array of unicode characters with a gap somewhere. The gap is moved to the location of changes to take advantage of common behavior where most changes are in the same location. Changes that occur at a gap boundary are generally cheap and moving the gap is generally cheaper than moving the array contents directly to accommodate the change.The positions tracking change are also generally cheap to maintain. The Position implementations (marks) store the array index and can easily calculate the sequential position from the current gap location. Changes only require update to the the marks between the old and new gap boundaries when the gap is moved, so generally updating the marks is pretty cheap. The marks are stored sorted so they can be located quickly with a binary search. This increases the cost of adding a mark, and decreases the cost of keeping the mark updated. - See Also:
- Serialized Form
 
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Constructor SummaryConstructors Constructor Description GapContent()Creates a new GapContent object.GapContent(int initialLength)Creates a new GapContent object, with the initial size specified.
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Method SummaryAll Methods Instance Methods Concrete Methods Modifier and Type Method Description protected ObjectallocateArray(int len)Allocate an array to store items of the type appropriate (which is determined by the subclass).PositioncreatePosition(int offset)Creates a position within the content that will track change as the content is mutated.protected ObjectgetArray()Access to the array.protected intgetArrayLength()Get the length of the allocated array.voidgetChars(int where, int len, Segment chars)Retrieves a portion of the content.protected intgetGapEnd()Access to the end of the gap.protected intgetGapStart()Access to the start of the gap.protected VectorgetPositionsInRange(Vector v, int offset, int length)Returns a Vector containing instances of UndoPosRef for the Positions in the rangeoffsettooffset+length.StringgetString(int where, int len)Retrieves a portion of the content.UndoableEditinsertString(int where, String str)Inserts a string into the content.intlength()Returns the length of the content.UndoableEditremove(int where, int nitems)Removes part of the content.protected voidreplace(int position, int rmSize, Object addItems, int addSize)Replace the given logical position in the storage with the given new items.protected voidresetMarksAtZero()Resets all the marks that have an offset of 0 to have an index of zero as well.protected voidshiftEnd(int newSize)Make the gap bigger, moving any necessary data and updating the appropriate marksprotected voidshiftGap(int newGapStart)Move the start of the gap to a new location, without changing the size of the gap.protected voidshiftGapEndUp(int newGapEnd)Adjust the gap end upward.protected voidshiftGapStartDown(int newGapStart)Adjust the gap end downward.protected voidupdateUndoPositions(Vector positions, int offset, int length)Resets the location for all the UndoPosRef instances inpositions.
 
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Constructor Detail- 
GapContentpublic GapContent() Creates a new GapContent object. Initial size defaults to 10.
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GapContentpublic GapContent(int initialLength) Creates a new GapContent object, with the initial size specified. The initial size will not be allowed to go below 2, to give room for the implied break and the gap.- Parameters:
- initialLength- the initial size
 
 
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Method Detail- 
allocateArrayprotected Object allocateArray(int len) Allocate an array to store items of the type appropriate (which is determined by the subclass).
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getArrayLengthprotected int getArrayLength() Get the length of the allocated array.
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lengthpublic int length() Returns the length of the content.- Specified by:
- lengthin interface- AbstractDocument.Content
- Returns:
- the length >= 1
- See Also:
- AbstractDocument.Content.length()
 
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insertStringpublic UndoableEdit insertString(int where, String str) throws BadLocationException Inserts a string into the content.- Specified by:
- insertStringin interface- AbstractDocument.Content
- Parameters:
- where- the starting position >= 0, < length()
- str- the non-null string to insert
- Returns:
- an UndoableEdit object for undoing
- Throws:
- BadLocationException- if the specified position is invalid
- See Also:
- AbstractDocument.Content.insertString(int, java.lang.String)
 
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removepublic UndoableEdit remove(int where, int nitems) throws BadLocationException Removes part of the content.- Specified by:
- removein interface- AbstractDocument.Content
- Parameters:
- where- the starting position >= 0, where + nitems < length()
- nitems- the number of characters to remove >= 0
- Returns:
- an UndoableEdit object for undoing
- Throws:
- BadLocationException- if the specified position is invalid
- See Also:
- AbstractDocument.Content.remove(int, int)
 
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getStringpublic String getString(int where, int len) throws BadLocationException Retrieves a portion of the content.- Specified by:
- getStringin interface- AbstractDocument.Content
- Parameters:
- where- the starting position >= 0
- len- the length to retrieve >= 0
- Returns:
- a string representing the content
- Throws:
- BadLocationException- if the specified position is invalid
- See Also:
- AbstractDocument.Content.getString(int, int)
 
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getCharspublic void getChars(int where, int len, Segment chars) throws BadLocationExceptionRetrieves a portion of the content. If the desired content spans the gap, we copy the content. If the desired content does not span the gap, the actual store is returned to avoid the copy since it is contiguous.- Specified by:
- getCharsin interface- AbstractDocument.Content
- Parameters:
- where- the starting position >= 0, where + len <= length()
- len- the number of characters to retrieve >= 0
- chars- the Segment object to return the characters in
- Throws:
- BadLocationException- if the specified position is invalid
- See Also:
- AbstractDocument.Content.getChars(int, int, javax.swing.text.Segment)
 
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createPositionpublic Position createPosition(int offset) throws BadLocationException Creates a position within the content that will track change as the content is mutated.- Specified by:
- createPositionin interface- AbstractDocument.Content
- Parameters:
- offset- the offset to track >= 0
- Returns:
- the position
- Throws:
- BadLocationException- if the specified position is invalid
 
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shiftEndprotected void shiftEnd(int newSize) Make the gap bigger, moving any necessary data and updating the appropriate marks
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shiftGapprotected void shiftGap(int newGapStart) Move the start of the gap to a new location, without changing the size of the gap. This moves the data in the array and updates the marks accordingly.
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resetMarksAtZeroprotected void resetMarksAtZero() Resets all the marks that have an offset of 0 to have an index of zero as well.
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shiftGapStartDownprotected void shiftGapStartDown(int newGapStart) Adjust the gap end downward. This doesn't move any data, but it does update any marks affected by the boundary change. All marks from the old gap start down to the new gap start are squeezed to the end of the gap (their location has been removed).
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shiftGapEndUpprotected void shiftGapEndUp(int newGapEnd) Adjust the gap end upward. This doesn't move any data, but it does update any marks affected by the boundary change. All marks from the old gap end up to the new gap end are squeezed to the end of the gap (their location has been removed).
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getPositionsInRangeprotected Vector getPositionsInRange(Vector v, int offset, int length) Returns a Vector containing instances of UndoPosRef for the Positions in the rangeoffsettooffset+length. Ifvis not null the matching Positions are placed in there. The vector with the resulting Positions are returned.- Parameters:
- v- the Vector to use, with a new one created on null
- offset- the starting offset >= 0
- length- the length >= 0
- Returns:
- the set of instances
 
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updateUndoPositionsprotected void updateUndoPositions(Vector positions, int offset, int length) Resets the location for all the UndoPosRef instances inpositions.This is meant for internal usage, and is generally not of interest to subclasses. - Parameters:
- positions- the UndoPosRef instances to reset
- offset- where the string was inserted
- length- length of inserted string
 
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getArrayprotected final Object getArray() Access to the array. The actual type of the array is known only by the subclass.
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getGapStartprotected final int getGapStart() Access to the start of the gap.
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getGapEndprotected final int getGapEnd() Access to the end of the gap.
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replaceprotected void replace(int position, int rmSize, Object addItems, int addSize)Replace the given logical position in the storage with the given new items. This will move the gap to the area being changed if the gap is not currently located at the change location.- Parameters:
- position- the location to make the replacement. This is not the location in the underlying storage array, but the location in the contiguous space being modeled.
- rmSize- the number of items to remove
- addItems- the new items to place in storage.
 
 
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