com.levigo.util.swing.glazedlists
Class AutoCompleteSupport<E>

java.lang.Object
  com.levigo.util.swing.glazedlists.AutoCompleteSupport<E>

public final class AutoCompleteSupport<E>
extends Object

This class install(javax.swing.JComboBox, com.levigo.util.base.glazedlists.EventList)s support for filtering and autocompletion into a standard JComboBox. It also acts as a factory class for creating autocompleting table cell editors.

All autocompletion behaviour provided is meant to mimic the functionality of the Firefox address field. To be explicit, the following is a list of expected behaviours which are installed:

Typing into the ComboBox Editor

1. typing any value into the editor when the popup is invisible causes the popup to appear and its contents to be filtered according to the editor's text. It also autocompletes to the first item that is prefixed with the editor's text and selects that item within the popup.
2. typing any value into the editor when the popup is visible causes the popup to be refiltered according to the editor's text and reselects an appropriate autocompletion item.
3. typing the down or up arrow keys in the editor when the popup is invisible causes the popup to appear and its contents to be filtered according to the editor's text. It also autocompletes to the first item that is prefixed with the editor's text and selects that item within the popup.
4. typing the up arrow key when the popup is visible and the selected element is the first element causes the autocompletion to be cleared and the popup's selection to be removed.
5. typing the up arrow key when no selection exists causes the last element of the popup to become selected and used for autocompletion
6. typing the down arrow key when the popup is visible and the selected element is the last element causes the autocompletion to be cleared and the popup's selection to be removed
7. typing the down arrow key when no selection exists causes the first element of the popup to become selected and used for autocompletion
8. typing the delete key while in strict mode will select the prior text rather than delete it. Attempting to delete all text results in a beep unless the autcomplete support has been configured to not beep.

Clicking on the Arrow Button

1. clicking the arrow button when the popup is invisible causes the popup to appear and its contents to be shown unfiltered
2. clicking the arrow button when the popup is visible causes the popup to be hidden

Sizing the ComboBox Popup

1. the popup is always at least as wide as the autocompleting JComboBox , but may be wider to accomodate a prototype display value if a non-null prototype display value exists
2. as items are filtered in the ComboBoxModel, the popup height is adjusted to display between 0 and JComboBox.getMaximumRowCount() rows before scrolling the popup

JComboBox ActionEvents

A single ActionEvent is fired from the JComboBox in these situations:

1. the user hits the enter key
2. the selected item within the popup is changed (which can happen due to a mouse click, a change in the autocompletion term, or using the arrow keys)
3. the JComboBox loses focus and contains a value that does not appear in the ComboBoxModel

Null Values in the ComboBoxModel

null values located in the ComboBoxModel are considered identical to empty Strings ("") for the purposes of locating autocompletion terms.

ComboBoxEditor Focus

1. the text in the ComboBoxEditor is selected if getSelectsTextOnFocusGain() returns true
2. the JPopupMenu is hidden when the ComboBoxEditor loses focus if getHidesPopupOnFocusLost() returns true

Extracting String Values

Each value in the ComboBoxModel must be converted to a String for many reasons: filtering, setting into the ComboBoxEditor, displaying in the renderer, etc. By default, JComboBox relies on Object.toString() to map elements to their String equivalents. Sometimes, however, toString() is not a reliable or desirable mechanism to use. To deal with this problem, AutoCompleteSupport provides an install method that takes a Format object which is used to do all converting back and forth between Strings and ComboBoxModel objects.

In order to achieve all of the autocompletion and filtering behaviour, the following occurs when install(javax.swing.JComboBox, com.levigo.util.base.glazedlists.EventList) is called:

• the JComboBox will be made editable
• the JComboBox will have a custom ComboBoxModel installed on it containing the given items
• the ComboBoxEditor will be wrapped with functionality and set back into the JComboBox as the editor
• the JTextField which is the editor component for the JComboBox will have a DocumentFilter installed on its backing Document

The strategy of this support class is to alter all of the objects which influence the behaviour of the JComboBox in one single context. With that achieved, it greatly reduces the cross-functional communication required to customize the behaviour of JComboBox for filtering and autocompletion.

Warning: This class must be mutated from the Swing Event Dispatch Thread. Failure to do so will result in an IllegalStateException thrown from any one of:

• install(JComboBox, EventList)
• install(JComboBox, EventList, TextFilterator)
• install(JComboBox, EventList, TextFilterator, Format)
• isInstalled()
• uninstall()
• setCorrectsCase(boolean)
• setStrict(boolean)
• setBeepOnStrictViolation(boolean)
• setSelectsTextOnFocusGain(boolean)
• setHidesPopupOnFocusLost(boolean)
• setFilterMode(int)
• setFirstItem(Object)
• removeFirstItem()

Author:

James Lemieux

Nested Class Summary

static class

AutoCompleteSupport.AutoCompleteCellEditor<E> This extension of DefaultCellEditor exists solely to provide a handle to the AutoCompleteSupport object that is providing autocompletion capabilities to the JComboBox.

Method Summary

static <E> AutoCompleteSupport.AutoCompleteCellEditor<E>	createTableCellEditor(Comparator uniqueComparator, TableFormat<E> tableFormat, EventList<E> tableData, int columnIndex) This factory method creates and returns a AutoCompleteSupport.AutoCompleteCellEditor which adapts an autocompleting JComboBox for use as a Table Cell Editor.
static <E> AutoCompleteSupport.AutoCompleteCellEditor<E>	createTableCellEditor(EventList<E> source) This factory method creates and returns a AutoCompleteSupport.AutoCompleteCellEditor which adapts an autocompleting JComboBox for use as a Table Cell Editor.
static <E> AutoCompleteSupport.AutoCompleteCellEditor<E>	createTableCellEditor(TableFormat<E> tableFormat, EventList<E> tableData, int columnIndex) This factory method creates and returns a AutoCompleteSupport.AutoCompleteCellEditor which adapts an autocompleting JComboBox for use as a Table Cell Editor.
boolean	getBeepOnStrictViolation() Returns true if a beep sound is played when the user attempts to violate the strict invariant; false if no beep sound is played.
JComboBox	getComboBox() Returns the autocompleting JComboBox or null if AutoCompleteSupport has been uninstall()ed.
boolean	getCorrectsCase() Returns true if user specified strings are converted to the case of the autocompletion term they match; false otherwise.
int	getFilterMode() Returns the manner in which the contents of the ComboBoxModel are filtered.
E	getFirstItem() Returns the optional single value used as the first element in the ComboBoxModel or null if no first item has been set.
boolean	getHidesPopupOnFocusLost() Returns true if the popup menu is hidden whenever the combo box editor loses focus; false otherwise.
EventList<E>	getItemList() Returns the filtered EventList of items which backs the ComboBoxModel of the autocompleting JComboBox.
boolean	getSelectsTextOnFocusGain() Returns true if the combo box editor text is selected when it gains focus; false otherwise.
TextFilterator<? super E>	getTextFilterator() Returns the TextFilterator that extracts searchable strings from each item in the ComboBoxModel.
Object	getTextMatchingStrategy() Returns the manner in which the contents of the ComboBoxModel are filtered and autocompletion terms are matched.
static <E> AutoCompleteSupport<E>	install(JComboBox comboBox, EventList<E> items) Installs support for autocompletion into the comboBox and returns the support object that is actually providing those facilities.
static <E> AutoCompleteSupport<E>	install(JComboBox comboBox, EventList<E> items, TextFilterator<? super E> filterator) Installs support for autocompletion into the comboBox and returns the support object that is actually providing those facilities.
static <E> AutoCompleteSupport<E>	install(JComboBox comboBox, EventList<E> items, TextFilterator<? super E> filterator, Format format) Installs support for autocompletion into the comboBox and returns the support object that is actually providing those facilities.
boolean	isInstalled() Returns true if this autocomplete support instance is currently installed and altering the behaviour of the combo box; false if it has been uninstall()ed.
boolean	isStrict() Returns true if the user is able to specify values which do not appear in the popup list of suggestions; false otherwise.
E	removeFirstItem() Removes and returns the optional single value used as the first element in the ComboBoxModel or null if no first item has been set.
void	setBeepOnStrictViolation(boolean beepOnStrictViolation) Sets the policy for indicating strict-mode violations to the user by way of a beep sound.
void	setCorrectsCase(boolean correctCase) If correctCase is true, user specified strings will be converted to the case of the element they match.
void	setFilterMode(int mode) Sets the manner in which the contents of the ComboBoxModel are filtered.
void	setFirstItem(E item) This method set a single optional value to be used as the first element in the ComboBoxModel.
void	setHidesPopupOnFocusLost(boolean hidesPopupOnFocusLost) If hidesPopupOnFocusLost is true, then the popup menu of the combo box is always hidden whenever the combo box editor loses focus.
void	setSelectsTextOnFocusGain(boolean selectsTextOnFocusGain) If selectsTextOnFocusGain is true, all text in the editor is selected when the combo box editor gains focus.
void	setStrict(boolean strict) If strict is false, the user can specify values not appearing within the ComboBoxModel.
void	setTextMatchingStrategy(Object strategy) Sets the manner in which the contents of the ComboBoxModel are filtered and autocompletion terms are matched.
void	uninstall() This method removes autocompletion support from the JComboBox it was installed on.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

install

public static <E> AutoCompleteSupport<E> install(JComboBox comboBox,
                                                 EventList<E> items)

Installs support for autocompletion into the comboBox and returns the support object that is actually providing those facilities. The support object is returned so that the caller may invoke uninstall() at some later time to remove the autocompletion features.

This method assumes that the items can be converted into reasonable String representations via Object.toString().

The following must be true in order to successfully install support for autocompletion on a JComboBox:

• The JComboBox must use a JTextField as its editor component
• The JTextField must use an AbstractDocument as its model

Parameters:

comboBox - the JComboBox to decorate with autocompletion

items - the objects to display in the comboBox

Returns:

an instance of the support class providing autocomplete features

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

install

public static <E> AutoCompleteSupport<E> install(JComboBox comboBox,
                                                 EventList<E> items,
                                                 TextFilterator<? super E> filterator)

Installs support for autocompletion into the comboBox and returns the support object that is actually providing those facilities. The support object is returned so that the caller may invoke uninstall() at some later time to remove the autocompletion features.

This method assumes that the items can be converted into reasonable String representations via Object.toString().

The filterator will be used to extract searchable text strings from each of the items. A null filterator implies the item's toString() method should be used when filtering it.

The following must be true in order to successfully install support for autocompletion on a JComboBox:

• The JComboBox must use a JTextField as its editor component
• The JTextField must use an AbstractDocument as its model

Parameters:

comboBox - the JComboBox to decorate with autocompletion

items - the objects to display in the comboBox

filterator - extracts searchable text strings from each item; null implies the item's toString() method should be used when filtering it

Returns:

an instance of the support class providing autocomplete features

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

install

public static <E> AutoCompleteSupport<E> install(JComboBox comboBox,
                                                 EventList<E> items,
                                                 TextFilterator<? super E> filterator,
                                                 Format format)

Installs support for autocompletion into the comboBox and returns the support object that is actually providing those facilities. The support object is returned so that the caller may invoke uninstall() at some later time to remove the autocompletion features.

This method uses the given format to convert the given items into Strings and back again. In other words, this method does NOT rely on Object.toString() to produce a reasonable String representation of each item. Likewise, it does not rely on the existence of a valueOf(String) method for creating items out of Strings as is the default behaviour of JComboBox.

It can be assumed that the only methods called on the given format are:

• Format.format(Object)
• Format.parseObject(String, ParsePosition)

As a convenience, this method will install a custom ListCellRenderer on the comboBox that displays the String value returned by the format. Though this is only done if the given format is not null and if the comboBox does not already use a custom renderer.

The filterator will be used to extract searchable text strings from each of the items. A null filterator implies one of two default strategies will be used. If the format is not null then the String value returned from the format object will be used when filtering a given item. Otherwise, the item's toString() method will be used when it is filtered.

The following must be true in order to successfully install support for autocompletion on a JComboBox:

• The JComboBox must use a JTextField as its editor component
• The JTextField must use an AbstractDocument as its model

Parameters:

comboBox - the JComboBox to decorate with autocompletion

items - the objects to display in the comboBox

filterator - extracts searchable text strings from each item. If the format is not null then the String value returned from the format object will be used when filtering a given item. Otherwise, the item's toString() method will be used when it is filtered.

format - a Format object capable of converting items into Strings and back. null indicates the standard JComboBox methods of converting are acceptable.

Returns:

an instance of the support class providing autocomplete features

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

getComboBox

public JComboBox getComboBox()

Returns the autocompleting JComboBox or null if AutoCompleteSupport has been uninstall()ed.

getTextFilterator

public TextFilterator<? super E> getTextFilterator()

Returns the TextFilterator that extracts searchable strings from each item in the ComboBoxModel.

getItemList

public EventList<E> getItemList()

Returns the filtered EventList of items which backs the ComboBoxModel of the autocompleting JComboBox.

getCorrectsCase

public boolean getCorrectsCase()

Returns true if user specified strings are converted to the case of the autocompletion term they match; false otherwise.

setCorrectsCase

public void setCorrectsCase(boolean correctCase)

If correctCase is true, user specified strings will be converted to the case of the element they match. Otherwise they will be left unaltered.

Note: this flag only has meeting when strict mode is turned off. When strict mode is on, case is corrected regardless of this setting.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

See Also:

setStrict(boolean)

isStrict

public boolean isStrict()

Returns true if the user is able to specify values which do not appear in the popup list of suggestions; false otherwise.

setStrict

public void setStrict(boolean strict)

If strict is false, the user can specify values not appearing within the ComboBoxModel. If it is true each keystroke must continue to match some value in the ComboBoxModel or it will be discarded.

Note: When strict mode is enabled, all user input is corrected to the case of the autocompletion term, regardless of the correctsCase setting.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

See Also:

setCorrectsCase(boolean)

getBeepOnStrictViolation

public boolean getBeepOnStrictViolation()

Returns true if a beep sound is played when the user attempts to violate the strict invariant; false if no beep sound is played. This setting is only respected if isStrict() returns true.

See Also:

setStrict(boolean)

setBeepOnStrictViolation

public void setBeepOnStrictViolation(boolean beepOnStrictViolation)

Sets the policy for indicating strict-mode violations to the user by way of a beep sound.

Parameters:

beepOnStrictViolation - true if a beep sound should be played when the user attempts to violate the strict invariant; false if no beep sound should be played

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

getSelectsTextOnFocusGain

public boolean getSelectsTextOnFocusGain()

Returns true if the combo box editor text is selected when it gains focus; false otherwise.

setSelectsTextOnFocusGain

public void setSelectsTextOnFocusGain(boolean selectsTextOnFocusGain)

If selectsTextOnFocusGain is true, all text in the editor is selected when the combo box editor gains focus. If it is false the selection state of the editor is not effected by focus changes.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

getHidesPopupOnFocusLost

public boolean getHidesPopupOnFocusLost()

Returns true if the popup menu is hidden whenever the combo box editor loses focus; false otherwise.

setHidesPopupOnFocusLost

public void setHidesPopupOnFocusLost(boolean hidesPopupOnFocusLost)

If hidesPopupOnFocusLost is true, then the popup menu of the combo box is always hidden whenever the combo box editor loses focus. If it is false the default behaviour is preserved. In practice this means that if focus is lost because of a MouseEvent, the behaviour is reasonable, but if focus is lost because of a KeyEvent (e.g. tabbing to the next focusable component) then the popup menu remains visible.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

getFilterMode

public int getFilterMode()

Returns the manner in which the contents of the ComboBoxModel are filtered. This method will return one of TextMatcherEditor.CONTAINS or TextMatcherEditor.STARTS_WITH.

TextMatcherEditor.CONTAINS indicates elements of the ComboBoxModel are matched when they contain the text entered by the user.

TextMatcherEditor.STARTS_WITH indicates elements of the ComboBoxModel are matched when they start with the text entered by the user.

In both modes, autocompletion only occurs when a given item starts with user-specified text. The filter mode only affects the filtering aspect of autocomplete support.

setFilterMode

public void setFilterMode(int mode)

Sets the manner in which the contents of the ComboBoxModel are filtered. The given mode must be one of TextMatcherEditor.CONTAINS or TextMatcherEditor.STARTS_WITH.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

See Also:

getFilterMode()

setTextMatchingStrategy

public void setTextMatchingStrategy(Object strategy)

Sets the manner in which the contents of the ComboBoxModel are filtered and autocompletion terms are matched. The given strategy must be one of TextMatcherEditor.IDENTICAL_STRATEGY or TextMatcherEditor.NORMALIZED_STRATEGY or the Unicode strategy of the ICU4J extension.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

See Also:

getTextMatchingStrategy()

getTextMatchingStrategy

public Object getTextMatchingStrategy()

Returns the manner in which the contents of the ComboBoxModel are filtered and autocompletion terms are matched. The returned strategy is one of TextMatcherEditor.IDENTICAL_STRATEGY or TextMatcherEditor.NORMALIZED_STRATEGY or the Unicode strategy of the ICU4J extension.

setFirstItem

public void setFirstItem(E item)

This method set a single optional value to be used as the first element in the ComboBoxModel. This value typically represents "no selection" or "blank". This value is always present and is not filtered away during autocompletion.

Parameters:

item - the first value to present in the ComboBoxModel

getFirstItem

public E getFirstItem()

Returns the optional single value used as the first element in the ComboBoxModel or null if no first item has been set.

Returns:

the special first value presented in the ComboBoxModel or null if no first item has been set

removeFirstItem

public E removeFirstItem()

Removes and returns the optional single value used as the first element in the ComboBoxModel or null if no first item has been set.

Returns:

the special first value presented in the ComboBoxModel or null if no first item has been set

isInstalled

public boolean isInstalled()

Returns true if this autocomplete support instance is currently installed and altering the behaviour of the combo box; false if it has been uninstall()ed.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

uninstall

public void uninstall()

This method removes autocompletion support from the JComboBox it was installed on. This method is useful when the EventList of items that backs the combo box must outlive the combo box itself. Calling this method will return the combo box to its original state before autocompletion was installed, and it will be available for garbage collection independently of the EventList of items.

Throws:

IllegalStateException - if this method is called from any Thread other than the Swing Event Dispatch Thread

createTableCellEditor

public static <E> AutoCompleteSupport.AutoCompleteCellEditor<E> createTableCellEditor(TableFormat<E> tableFormat,
                                                                                      EventList<E> tableData,
                                                                                      int columnIndex)

This factory method creates and returns a AutoCompleteSupport.AutoCompleteCellEditor which adapts an autocompleting JComboBox for use as a Table Cell Editor. The values within the table column are used as autocompletion terms within the ComboBoxModel.

This version of createTableCellEditor assumes that the values stored in the TableModel at the given columnIndex are all Comparable, and that the natural ordering defined by those Comparable values also determines which are duplicates (and thus can safely be removed) and which are unique (and thus must remain in the ComboBoxModel).

Note that this factory method is only appropriate for use when the values in the ComboBoxModel should be the unique set of values in a table column. If some other list of values will be used then createTableCellEditor(EventList) is the appropriate factory method to use.

If the appearance or function of the autocompleting JComboBox is to be customized, it can be retrieved using DefaultCellEditor.getComponent().

Parameters:

tableFormat - specifies how each row object within a table is broken apart into column values

tableData - the EventList backing the TableModel

columnIndex - the index of the column for which to return a AutoCompleteSupport.AutoCompleteCellEditor

Returns:

a AutoCompleteSupport.AutoCompleteCellEditor which contains an autocompleting combobox whose contents remain consistent with the data in the table column at the given columnIndex

createTableCellEditor

public static <E> AutoCompleteSupport.AutoCompleteCellEditor<E> createTableCellEditor(Comparator uniqueComparator,
                                                                                      TableFormat<E> tableFormat,
                                                                                      EventList<E> tableData,
                                                                                      int columnIndex)

This factory method creates and returns a AutoCompleteSupport.AutoCompleteCellEditor which adapts an autocompleting JComboBox for use as a Table Cell Editor. The values within the table column are used as autocompletion terms within the ComboBoxModel.

This version of createTableCellEditor makes no assumption about the values stored in the TableModel at the given columnIndex. Instead, it uses the given uniqueComparator to determine which values are duplicates (and thus can safely be removed) and which are unique (and thus must remain in the ComboBoxModel).

Note that this factory method is only appropriate for use when the values in the ComboBoxModel should be the unique set of values in a table column. If some other list of values will be used then createTableCellEditor(EventList) is the appropriate factory method to use.

If the appearance or function of the autocompleting JComboBox is to be customized, it can be retrieved using DefaultCellEditor.getComponent().

Parameters:

uniqueComparator - the Comparator that strips away duplicate elements from the ComboBoxModel

tableFormat - specifies how each row object within a table is broken apart into column values

tableData - the EventList backing the TableModel

columnIndex - the index of the column for which to return a AutoCompleteSupport.AutoCompleteCellEditor

Returns:

a AutoCompleteSupport.AutoCompleteCellEditor which contains an autocompleting combobox whose contents remain consistent with the data in the table column at the given columnIndex

createTableCellEditor

public static <E> AutoCompleteSupport.AutoCompleteCellEditor<E> createTableCellEditor(EventList<E> source)

This factory method creates and returns a AutoCompleteSupport.AutoCompleteCellEditor which adapts an autocompleting JComboBox for use as a Table Cell Editor. The values within the source are used as autocompletion terms within the ComboBoxModel.

If the appearance or function of the autocompleting JComboBox is to be customized, it can be retrieved using DefaultCellEditor.getComponent().

Parameters:

source - the source of data for the JComboBox within the table cell editor

Returns:

a AutoCompleteSupport.AutoCompleteCellEditor which contains an autocompleting combobox whose model contents are determined by the given source