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javax.swing.text

public Interface Caret

Known Direct Implementers
javax.swing.text.DefaultCaret
Imports
java.awt.Graphics, .Point, javax.swing.Action, javax.swing.event.ChangeListener
A place within a document view that represents where things can be inserted into the document model. A caret has a position in the document referred to as a dot. The dot is where the caret is currently located in the model. There is a second position maintained by the caret that represents the other end of a selection called mark. If there is no selection the dot and mark will be equal. If a selection exists, the two values will be different.

The dot can be placed by either calling setDot or moveDot. Setting the dot has the effect of removing any selection that may have previously existed. The dot and mark will be equal. Moving the dot has the effect of creating a selection as the mark is left at whatever position it previously had.

Author
Timothy Prinzing

Method Summary

Modifier and TypeMethod and Description
public void
addChangeListener(ChangeListener
the change listener
l)

Adds a listener to track whenever the caret position has been changed.

public void
deinstall(JTextComponent
the JTextComponent
c)

Called when the UI is being removed from the interface of a JTextComponent.

public int

Returns:

the delay in milliseconds >=0. If this is zero the caret will not blink.
getBlinkRate()

Gets the blink rate of the caret.

public int

Returns:

the position >=0
getDot()

Fetches the current position of the caret.

public Point

Returns:

the visual position.
getMagicCaretPosition()

Gets the current caret visual location.

public int

Returns:

the position >=0
getMark()

Fetches the current position of the mark.

public void
install(JTextComponent
the JTextComponent
c)

Called when the UI is being installed into the interface of a JTextComponent.

public boolean

Returns:

true if the caret is visible else false
isSelectionVisible()

Determines if the selection is currently visible.

public boolean

Returns:

true if the caret is visible else false
isVisible()

Determines if the caret is currently visible.

public void
moveDot(int
the new position to move the caret to >=0
dot)

Moves the caret position (dot) to some other position, leaving behind the mark.

public void
paint(Graphics
the graphics context
g)

Renders the caret.

public void
removeChangeListener(ChangeListener
the change listener
l)

Removes a listener that was tracking caret position changes.

public void
setBlinkRate(int
the delay in milliseconds >=0. If this is zero the caret will not blink.
rate)

Sets the blink rate of the caret.

public void
setDot(int
the new position to set the caret to
dot)

Sets the caret position to some position.

public void
setMagicCaretPosition(Point
the Point to use for the saved position. This can be null to indicate there is no visual location.
p)

Set the current caret visual location.

public void
setSelectionVisible(boolean
true if the caret should be shown, and false if the caret should be hidden
v)

Sets the visibility of the selection

public void
setVisible(boolean
true if the caret should be shown, and false if the caret should be hidden
v)

Sets the visibility of the caret.

Method Detail

addChangeListenerback to summary
public void addChangeListener(ChangeListener l)

Adds a listener to track whenever the caret position has been changed.

Parameters
l:ChangeListener

the change listener

deinstallback to summary
public void deinstall(JTextComponent c)

Called when the UI is being removed from the interface of a JTextComponent. This is used to unregister any listeners that were attached.

Parameters
c:JTextComponent

the JTextComponent

getBlinkRateback to summary
public int getBlinkRate()

Gets the blink rate of the caret. This determines if and how fast the caret blinks, commonly used as one way to attract attention to the caret.

Returns:int

the delay in milliseconds >=0. If this is zero the caret will not blink.

getDotback to summary
public int getDot()

Fetches the current position of the caret.

Returns:int

the position >=0

getMagicCaretPositionback to summary
public Point getMagicCaretPosition()

Gets the current caret visual location.

Returns:Point

the visual position.

See Also
setMagicCaretPosition
getMarkback to summary
public int getMark()

Fetches the current position of the mark. If there is a selection, the mark will not be the same as the dot.

Returns:int

the position >=0

installback to summary
public void install(JTextComponent c)

Called when the UI is being installed into the interface of a JTextComponent. This can be used to gain access to the model that is being navigated by the implementation of this interface.

Parameters
c:JTextComponent

the JTextComponent

isSelectionVisibleback to summary
public boolean isSelectionVisible()

Determines if the selection is currently visible.

Returns:boolean

true if the caret is visible else false

isVisibleback to summary
public boolean isVisible()

Determines if the caret is currently visible.

Returns:boolean

true if the caret is visible else false

moveDotback to summary
public void moveDot(int dot)

Moves the caret position (dot) to some other position, leaving behind the mark. This is useful for making selections.

Parameters
dot:int

the new position to move the caret to >=0

paintback to summary
public void paint(Graphics g)

Renders the caret. This method is called by UI classes.

Parameters
g:Graphics

the graphics context

removeChangeListenerback to summary
public void removeChangeListener(ChangeListener l)

Removes a listener that was tracking caret position changes.

Parameters
l:ChangeListener

the change listener

setBlinkRateback to summary
public void setBlinkRate(int rate)

Sets the blink rate of the caret. This determines if and how fast the caret blinks, commonly used as one way to attract attention to the caret.

Parameters
rate:int

the delay in milliseconds >=0. If this is zero the caret will not blink.

setDotback to summary
public void setDot(int dot)

Sets the caret position to some position. This causes the mark to become the same as the dot, effectively setting the selection range to zero.

If the parameter is negative or beyond the length of the document, the caret is placed at the beginning or at the end, respectively.

Parameters
dot:int

the new position to set the caret to

setMagicCaretPositionback to summary
public void setMagicCaretPosition(Point p)

Set the current caret visual location. This can be used when moving between lines that have uneven end positions (such as when caret up or down actions occur). If text flows left-to-right or right-to-left the x-coordinate will indicate the desired navigation location for vertical movement. If the text flow is top-to-bottom, the y-coordinate will indicate the desired navigation location for horizontal movement.

Parameters
p:Point

the Point to use for the saved position. This can be null to indicate there is no visual location.

setSelectionVisibleback to summary
public void setSelectionVisible(boolean v)

Sets the visibility of the selection

Parameters
v:boolean

true if the caret should be shown, and false if the caret should be hidden

setVisibleback to summary
public void setVisible(boolean v)

Sets the visibility of the caret.

Parameters
v:boolean

true if the caret should be shown, and false if the caret should be hidden