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Eclipse Platform
Release 3.5

org.eclipse.jface.preference
Class FieldEditor

java.lang.Object
  extended by 
org.eclipse.jface.preference.FieldEditor
Direct Known Subclasses:
AbstractEncodingFieldEditor, BooleanFieldEditor, ColorFieldEditor, ComboFieldEditor, FontFieldEditor, ListEditor, RadioGroupFieldEditor, ScaleFieldEditor, StringFieldEditor

public abstract class FieldEditor
extends Object

Abstract base class for all field editors.

A field editor presents the value of a preference to the end user. The value is loaded from a preference store; if modified by the end user, the value is validated and eventually stored back to the preference store. A field editor reports an event when the value, or the validity of the value, changes.

Field editors should be used in conjunction with a field editor preference page (FieldEditorPreferencePage) which coordinates everything and provides the message line which display messages emanating from the editor.

This package contains ready-to-use field editors for various types of preferences:

  • BooleanFieldEditor - booleans
  • IntegerFieldEditor - integers
  • StringFieldEditor - text strings
  • RadioGroupFieldEditor - enumerations
  • ColorFieldEditor - RGB colors
  • FontFieldEditor - fonts
  • DirectoryFieldEditor - directories
  • FileFieldEditor - files
  • PathEditor - paths


Field Summary
protected static int HORIZONTAL_GAP
          Gap between label and control.
static  String IS_VALID
          Property name constant (value "field_editor_is_valid") to signal a change in the validity of the value of this field editor.
static  String VALUE
          Property name constant (value "field_editor_value") to signal a change in the value of this field editor.
 
Constructor Summary
protected FieldEditor ()
          Creates a new field editor.
protected FieldEditor ( String name, String labelText, Composite parent)
          Creates a new field editor.
 
Method Summary
protected abstract  void adjustForNumColumns (int numColumns)
          Adjusts the horizontal span of this field editor's basic controls.
protected  void applyFont ()
          Applies a font.
protected  void checkParent ( Control control, Composite parent)
          Checks if the given parent is the current parent of the supplied control; throws an (unchecked) exception if they are not correctly related.
protected  void clearErrorMessage ()
          Clears the error message from the message line.
protected  void clearMessage ()
          Clears the normal message from the message line.
protected  int convertHorizontalDLUsToPixels ( Control control, int dlus)
          Returns the number of pixels corresponding to the given number of horizontal dialog units.
protected  int convertVerticalDLUsToPixels ( Control control, int dlus)
          Returns the number of pixels corresponding to the given number of vertical dialog units.
protected  void createControl ( Composite parent)
          Creates this field editor's main control containing all of its basic controls.
 void dispose ()
          Disposes the SWT resources used by this field editor.
protected abstract  void doFillIntoGrid ( Composite parent, int numColumns)
          Fills this field editor's basic controls into the given parent.
protected abstract  void doLoad ()
          Initializes this field editor with the preference value from the preference store.
protected abstract  void doLoadDefault ()
          Initializes this field editor with the default preference value from the preference store.
protected abstract  void doStore ()
          Stores the preference value from this field editor into the preference store.
 void fillIntoGrid ( Composite parent, int numColumns)
          Fills this field editor's basic controls into the given parent.
protected  void fireStateChanged ( String property, boolean oldValue, boolean newValue)
          Informs this field editor's listener, if it has one, about a change to one of this field editor's boolean-valued properties.
protected  void fireValueChanged ( String property, Object oldValue, Object newValue)
          Informs this field editor's listener, if it has one, about a change to one of this field editor's properties.
  String getFieldEditorFontName ()
          Returns the symbolic font name used by this field editor.
protected   Label getLabelControl ()
          Returns the label control.
  Label getLabelControl ( Composite parent)
          Returns this field editor's label component.
  String getLabelText ()
          Returns this field editor's label text.
abstract  int getNumberOfControls ()
          Returns the number of basic controls this field editor consists of.
protected   DialogPage getPage ()
          Return the DialogPage that the receiver is sending updates to.
  String getPreferenceName ()
          Returns the name of the preference this field editor operates on.
protected   PreferencePage getPreferencePage ()
          Deprecated. use #getPage()
  IPreferenceStore getPreferenceStore ()
          Returns the preference store used by this field editor.
protected  void init ( String name, String text)
          Initialize the field editor with the given preference name and label.
 boolean isValid ()
          Returns whether this field editor contains a valid value.
 void load ()
          Initializes this field editor with the preference value from the preference store.
 void loadDefault ()
          Initializes this field editor with the default preference value from the preference store.
 boolean presentsDefaultValue ()
          Returns whether this field editor currently presents the default value for its preference.
protected  void refreshValidState ()
          Refreshes this field editor's valid state after a value change and fires an IS_VALID property change event if warranted.
protected  void setButtonLayoutData ( Button button)
          Set the GridData on button to be one that is spaced for the current font.
 void setEnabled (boolean enabled, Composite parent)
          Set whether or not the controls in the field editor are enabled.
 void setFocus ()
          Sets the focus to this field editor.
 void setLabelText ( String text)
          Sets this field editor's label text.
 void setPage ( DialogPage dialogPage)
          Set the page to be the receiver.
 void setPreferenceName ( String name)
          Sets the name of the preference this field editor operates on.
 void setPreferencePage ( PreferencePage preferencePage)
          Deprecated. use #setPage(DialogPage)
 void setPreferenceStore ( IPreferenceStore store)
          Sets the preference store used by this field editor.
protected  void setPresentsDefaultValue (boolean booleanValue)
          Sets whether this field editor is presenting the default value.
 void setPropertyChangeListener ( IPropertyChangeListener listener)
          Sets or removes the property change listener for this field editor.
protected  void showErrorMessage ( String msg)
          Shows the given error message in the page for this field editor if it has one.
protected  void showMessage ( String msg)
          Shows the given message in the page for this field editor if it has one.
 void store ()
          Stores this field editor's value back into the preference store.
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

IS_VALID

public static final 
String IS_VALID
Property name constant (value "field_editor_is_valid") to signal a change in the validity of the value of this field editor.

See Also:
Constant Field Values

VALUE

public static final 
String VALUE
Property name constant (value "field_editor_value") to signal a change in the value of this field editor.

See Also:
Constant Field Values

HORIZONTAL_GAP

protected static final int HORIZONTAL_GAP
Gap between label and control.

See Also:
Constant Field Values
Constructor Detail

FieldEditor

protected FieldEditor()
Creates a new field editor.


FieldEditor

protected FieldEditor(
String name,
                      
String labelText,
                      
Composite parent)
Creates a new field editor.

Parameters:
name - the name of the preference this field editor works on
labelText - the label text of the field editor
parent - the parent of the field editor's control
Method Detail

adjustForNumColumns

protected abstract void adjustForNumColumns(int numColumns)
Adjusts the horizontal span of this field editor's basic controls.

Subclasses must implement this method to adjust the horizontal span of controls so they appear correct in the given number of columns.

The number of columns will always be equal to or greater than the value returned by this editor's getNumberOfControls method.

Parameters:
numColumns - the number of columns

applyFont

protected void applyFont()
Applies a font.

The default implementation of this framework method does nothing. Subclasses should override this method if they want to change the font of the SWT control to a value different than the standard dialog font.


checkParent

protected void checkParent(
Control control,
                           
Composite parent)
Checks if the given parent is the current parent of the supplied control; throws an (unchecked) exception if they are not correctly related.

Parameters:
control - the control
parent - the parent control

clearErrorMessage

protected void clearErrorMessage()
Clears the error message from the message line.


clearMessage

protected void clearMessage()
Clears the normal message from the message line.


convertHorizontalDLUsToPixels

protected int convertHorizontalDLUsToPixels(
Control control,
                                            int dlus)
Returns the number of pixels corresponding to the given number of horizontal dialog units.

Clients may call this framework method, but should not override it.

Parameters:
control - the control being sized
dlus - the number of horizontal dialog units
Returns:
the number of pixels

convertVerticalDLUsToPixels

protected int convertVerticalDLUsToPixels(
Control control,
                                          int dlus)
Returns the number of pixels corresponding to the given number of vertical dialog units.

Clients may call this framework method, but should not override it.

Parameters:
control - the control being sized
dlus - the number of vertical dialog units
Returns:
the number of pixels

createControl

protected void createControl(
Composite parent)
Creates this field editor's main control containing all of its basic controls.

Parameters:
parent - the parent control

dispose

public void dispose()
Disposes the SWT resources used by this field editor.


doFillIntoGrid

protected abstract void doFillIntoGrid(
Composite parent,
                                       int numColumns)
Fills this field editor's basic controls into the given parent.

Subclasses must implement this method to create the controls for this field editor.

Note this method may be called by the constructor, so it must not access fields on the receiver object because they will not be fully initialized.

Parameters:
parent - the composite used as a parent for the basic controls; the parent's layout must be a GridLayout
numColumns - the number of columns

doLoad

protected abstract void doLoad()
Initializes this field editor with the preference value from the preference store.

Subclasses must implement this method to properly initialize the field editor.


doLoadDefault

protected abstract void doLoadDefault()
Initializes this field editor with the default preference value from the preference store.

Subclasses must implement this method to properly initialize the field editor.


doStore

protected abstract void doStore()
Stores the preference value from this field editor into the preference store.

Subclasses must implement this method to save the entered value into the preference store.


fillIntoGrid

public void fillIntoGrid(
Composite parent,
                         int numColumns)
Fills this field editor's basic controls into the given parent.

Parameters:
parent - the composite used as a parent for the basic controls; the parent's layout must be a GridLayout
numColumns - the number of columns

fireStateChanged

protected void fireStateChanged(
String property,
                                boolean oldValue,
                                boolean newValue)
Informs this field editor's listener, if it has one, about a change to one of this field editor's boolean-valued properties. Does nothing if the old and new values are the same.

Parameters:
property - the field editor property name, such as VALUE or IS_VALID
oldValue - the old value
newValue - the new value

fireValueChanged

protected void fireValueChanged(
String property,
                                
Object oldValue,
                                
Object newValue)
Informs this field editor's listener, if it has one, about a change to one of this field editor's properties.

Parameters:
property - the field editor property name, such as VALUE or IS_VALID
oldValue - the old value object, or null
newValue - the new value, or null

getFieldEditorFontName

public 
String getFieldEditorFontName()
Returns the symbolic font name used by this field editor.

Returns:
the symbolic font name

getLabelControl

protected 
Label getLabelControl()
Returns the label control.

Returns:
the label control, or null if no label control has been created

getLabelControl

public 
Label getLabelControl(
Composite parent)
Returns this field editor's label component.

The label is created if it does not already exist

Parameters:
parent - the parent
Returns:
the label control

getLabelText

public 
String getLabelText()
Returns this field editor's label text.

Returns:
the label text

getNumberOfControls

public abstract int getNumberOfControls()
Returns the number of basic controls this field editor consists of.

Returns:
the number of controls

getPreferenceName

public 
String getPreferenceName()
Returns the name of the preference this field editor operates on.

Returns:
the name of the preference

getPreferencePage

protected 
PreferencePage getPreferencePage()
Deprecated. use #getPage()

Returns the preference page in which this field editor appears.

Returns:
the preference page, or null if none

getPage

protected 
DialogPage getPage()
Return the DialogPage that the receiver is sending updates to.

Returns:
DialogPage or null if it has not been set.
Since:
3.1

getPreferenceStore

public 
IPreferenceStore getPreferenceStore()
Returns the preference store used by this field editor.

Returns:
the preference store, or null if none
See Also:
setPreferenceStore(org.eclipse.jface.preference.IPreferenceStore)

init

protected void init(
String name,
                    
String text)
Initialize the field editor with the given preference name and label.

Parameters:
name - the name of the preference this field editor works on
text - the label text of the field editor

isValid

public boolean isValid()
Returns whether this field editor contains a valid value.

The default implementation of this framework method returns true. Subclasses wishing to perform validation should override both this method and refreshValidState.

Returns:
true if the field value is valid, and false if invalid
See Also:
refreshValidState()

load

public void load()
Initializes this field editor with the preference value from the preference store.


loadDefault

public void loadDefault()
Initializes this field editor with the default preference value from the preference store.


presentsDefaultValue

public boolean presentsDefaultValue()
Returns whether this field editor currently presents the default value for its preference.

Returns:
true if the default value is presented, and false otherwise

refreshValidState

protected void refreshValidState()
Refreshes this field editor's valid state after a value change and fires an IS_VALID property change event if warranted.

The default implementation of this framework method does nothing. Subclasses wishing to perform validation should override both this method and isValid.

See Also:
isValid()

setFocus

public void setFocus()
Sets the focus to this field editor.

The default implementation of this framework method does nothing. Subclasses may reimplement.


setLabelText

public void setLabelText(
String text)
Sets this field editor's label text. The label is typically presented to the left of the entry field.

Parameters:
text - the label text

setPreferenceName

public void setPreferenceName(
String name)
Sets the name of the preference this field editor operates on.

The ability to change this allows the same field editor object to be reused for different preferences.

For example:

        ...
  editor.setPreferenceName("font");
        editor.load();
 

Parameters:
name - the name of the preference

setPreferencePage

public void setPreferencePage(
PreferencePage preferencePage)
Deprecated. use #setPage(DialogPage)

Sets the preference page in which this field editor appears.

Parameters:
preferencePage - the preference page, or null if none

setPage

public void setPage(
DialogPage dialogPage)
Set the page to be the receiver.

Parameters:
dialogPage -
Since:
3.1

setPreferenceStore

public void setPreferenceStore(
IPreferenceStore store)
Sets the preference store used by this field editor.

Parameters:
store - the preference store, or null if none
See Also:
getPreferenceStore()

setPresentsDefaultValue

protected void setPresentsDefaultValue(boolean booleanValue)
Sets whether this field editor is presenting the default value.

Parameters:
booleanValue - true if the default value is being presented, and false otherwise

setPropertyChangeListener

public void setPropertyChangeListener(
IPropertyChangeListener listener)
Sets or removes the property change listener for this field editor.

Note that field editors can support only a single listener.

Parameters:
listener - a property change listener, or null to remove

showErrorMessage

protected void showErrorMessage(
String msg)
Shows the given error message in the page for this field editor if it has one.

Parameters:
msg - the error message

showMessage

protected void showMessage(
String msg)
Shows the given message in the page for this field editor if it has one.

Parameters:
msg - the message

store

public void store()
Stores this field editor's value back into the preference store.


setButtonLayoutData

protected void setButtonLayoutData(
Button button)
Set the GridData on button to be one that is spaced for the current font.

Parameters:
button - the button the data is being set on.

setEnabled

public void setEnabled(boolean enabled,
                       
Composite parent)
Set whether or not the controls in the field editor are enabled.

Parameters:
enabled - The enabled state.
parent - The parent of the controls in the group. Used to create the controls if required.

Eclipse Platform
Release 3.5

Guidelines for using Eclipse APIs.

Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire