Class java.awt.TextComponent - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

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Class java.awt.TextComponent

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.TextComponent

public class TextComponent
extends Component

The TextComponent class is the superclass of any component that allows the editing of some text.

A text component embodies a string of text. The TextComponent class defines a set of methods that determine whether or not this text is editable. If the component is editable, it defines another set of methods that supports a text insertion caret.

In addition, the class defines methods that are used to maintain a current selection from the text. The text selection, a substring of the component's text, is the target of editing operations. It is also referred to as the selected text.

textListener

addTextListener(TextListener): Adds the specified text event listener to recieve text events from this textcomponent.
getCaretPosition(): Gets the position of the text insertion caret for this text component.
getSelectedText(): Gets the selected text from the text that is presented by this text component.
getSelectionEnd(): Gets the end position of the selected text in this text component.
getSelectionStart(): Gets the start position of the selected text in this text component.
getText(): Gets the text that is presented by this text component.
isEditable(): Indicates whether or not this text component is editable.
paramString(): Returns the parameter string representing the state of this text component.
processEvent(AWTEvent): Processes events on this textcomponent.
processTextEvent(TextEvent): Processes text events occurring on this text component by dispatching them to any registered TextListener objects.
removeNotify(): Removes the TextComponent's peer.
removeTextListener(TextListener): Removes the specified text event listener so that it no longer receives text events from this textcomponent
select(int, int): Selects the text between the specified start and end positions.
selectAll(): Selects all the text in this text component.
setCaretPosition(int): Sets the position of the text insertion caret for this text component.
setEditable(boolean): Sets the flag that determines whether or not this text component is editable.
setSelectionEnd(int): Sets the selection end for this text component to the specified position.
setSelectionStart(int): Sets the selection start for this text component to the specified position.
setText(String): Sets the text that is presented by this text component to be the specified text.

textListener

 protected transient TextListener textListener

removeNotify

 public void removeNotify()

Removes the TextComponent's peer. The peer allows us to modify the appearance of the TextComponent without changing its functionality.

Overrides:: removeNotify in class Component

setText

 public synchronized void setText(String t)

Sets the text that is presented by this text component to be the specified text.

Parameters:: t - the new text.
See Also:: getText

getText

 public synchronized String getText()

Gets the text that is presented by this text component.

See Also:: setText

getSelectedText

 public synchronized String getSelectedText()

Gets the selected text from the text that is presented by this text component.

Returns:: the selected text of this text component.
See Also:: select

isEditable

 public boolean isEditable()

Indicates whether or not this text component is editable.

Returns:: true if this text component is editable; false otherwise.
See Also:: setEditable

setEditable

 public synchronized void setEditable(boolean b)

Sets the flag that determines whether or not this text component is editable.

If the flag is set to true, this text component becomes user editable. If the flag is set to false, the user cannot change the text of this text component.

Parameters:: t - a flag indicating whether this text component should be user editable.
See Also:: isEditable

getSelectionStart

 public synchronized int getSelectionStart()

Gets the start position of the selected text in this text component.

Returns:: the start position of the selected text.
See Also:: setSelectionStart, getSelectionEnd

setSelectionStart

 public synchronized void setSelectionStart(int selectionStart)

Sets the selection start for this text component to the specified position. The new start point is constrained to be at or before the current selection end. It also cannot be set to less than zero, the beginning of the component's text. If the caller supplies a value for selectionStart that is out of bounds, the method enforces these constraints silently, and without failure.

Parameters:: selectionStart - the start position of the selected text.
See Also:: getSelectionStart, setSelectionEnd

getSelectionEnd

 public synchronized int getSelectionEnd()

Gets the end position of the selected text in this text component.

Returns:: the end position of the selected text.
See Also:: setSelectionEnd, getSelectionStart

setSelectionEnd

 public synchronized void setSelectionEnd(int selectionEnd)

Sets the selection end for this text component to the specified position. The new end point is constrained to be at or after the current selection start. It also cannot be set beyond the end of the component's text. If the caller supplies a value for selectionEnd that is out of bounds, the method enforces these constraints silently, and without failure.

Parameters:: selectionEnd - the end position of the selected text.
See Also:: getSelectionEnd, setSelectionStart

select

 public synchronized void select(int selectionStart,
                                 int selectionEnd)

Selects the text between the specified start and end positions.

This method sets the start and end positions of the selected text, enforcing the restriction that the end position must be greater than or equal to the start position. The start position must be greater than zero, and the end position must be less that or equal to the length of the text component's text. If the caller supplies values that are inconsistent or out of bounds, the method enforces these constraints silently, and without failure.

Parameters:: selectionStart - the start position of the text to select.; selectionEnd - the end position of the text to select.
See Also:: setSelectionStart, setSelectionEnd, selectAll

selectAll

 public synchronized void selectAll()

Selects all the text in this text component.

See Also:: TextComponent@select

setCaretPosition

 public synchronized void setCaretPosition(int position)

Sets the position of the text insertion caret for this text component.

Parameters:: position - the position of the text insertion caret.
Throws: IllegalArgumentException: if the value supplied for position is less than zero.

getCaretPosition

 public synchronized int getCaretPosition()

Gets the position of the text insertion caret for this text component.

Returns:: the position of the text insertion caret.

addTextListener

 public synchronized void addTextListener(TextListener l)

Adds the specified text event listener to recieve text events from this textcomponent.

Parameters:: l - the text event listener

removeTextListener

 public synchronized void removeTextListener(TextListener l)

Removes the specified text event listener so that it no longer receives text events from this textcomponent

processEvent

 protected void processEvent(AWTEvent e)

Processes events on this textcomponent. If the event is a TextEvent, it invokes the processTextEvent method, else it invokes its superclass's processEvent.

Parameters:: e - the event
Overrides:: processEvent in class Component

processTextEvent

 protected void processTextEvent(TextEvent e)

Processes text events occurring on this text component by dispatching them to any registered TextListener objects. NOTE: This method will not be called unless text events are enabled for this component; this happens when one of the following occurs: a) A TextListener object is registered via addTextListener() b) Text events are enabled via enableEvents()

Parameters:: e - the text event
See Also:: enableEvents

paramString

 protected String paramString()

Returns the parameter string representing the state of this text component. This string is useful for debugging.

Returns:: the parameter string of this text component.
Overrides:: paramString in class Component

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