javax.microedition.lcdui
Class ChoiceGroup

java.lang.Object
  javax.microedition.lcdui.Item
      javax.microedition.lcdui.ChoiceGroup

All Implemented Interfaces:

Choice

public class ChoiceGroup
extends Item
implements Choice

A ChoiceGroup is a group of selectable elements intended to be placed within a Form. The group may be created with a mode that requires a single choice to be made or that allows multiple choices. The implementation is responsible for providing the graphical representation of these modes and must provide visually different graphics for different modes. For example, it might use "radio buttons" for the single choice mode and "check boxes" for the multiple choice mode.

Note: most of the essential methods have been specified in the Choice interface.

Field Summary

Fields inherited from class javax.microedition.lcdui.Item

BUTTON, HYPERLINK, LAYOUT_2, LAYOUT_BOTTOM, LAYOUT_CENTER, LAYOUT_DEFAULT, LAYOUT_EXPAND, LAYOUT_LEFT, LAYOUT_NEWLINE_AFTER, LAYOUT_NEWLINE_BEFORE, LAYOUT_RIGHT, LAYOUT_SHRINK, LAYOUT_TOP, LAYOUT_VCENTER, LAYOUT_VEXPAND, LAYOUT_VSHRINK, PLAIN

Fields inherited from interface javax.microedition.lcdui.Choice

EXCLUSIVE, IMPLICIT, MULTIPLE, POPUP, TEXT_WRAP_DEFAULT, TEXT_WRAP_OFF, TEXT_WRAP_ON

Constructor Summary

ChoiceGroup(String label, int choiceType)
Creates a new, empty ChoiceGroup, specifying its title and its type.

ChoiceGroup(String label, int choiceType, String[] stringElements, Image[] imageElements)
Creates a new ChoiceGroup, specifying its title, the type of the ChoiceGroup, and an array of Strings and Images to be used as its initial contents.

Method Summary
int	append(String stringPart, Image imagePart) Appends an element to the Choice.
void	delete(int elementNum) Deletes the element referenced by elementNum.
void	deleteAll() Deletes all elements from this ChoiceGroup.
int	getFitPolicy() Gets the application's preferred policy for fitting Choice element contents to the available screen space.
Font	getFont(int elementNum) Gets the application's preferred font for rendering the specified element of this Choice.
Image	getImage(int elementNum) Gets the Image part of the element referenced by elementNum.
String	getLabel() Gets the label of this Item object.
int	getLayout() Gets the layout directives used for placing the item.
int	getSelectedFlags(boolean[] selectedArray_return) Queries the state of a ChoiceGroup and returns the state of all elements in the boolean array selectedArray_return.
int	getSelectedIndex() Returns the index number of an element in the ChoiceGroup that is selected.
String	getString(int elementNum) Gets the String part of the element referenced by elementNum.
void	insert(int elementNum, String stringElement, Image imageElement) Inserts an element into the Choice just prior to the element specified.
boolean	isSelected(int elementNum) Gets a boolean value indicating whether this element is selected.
void	set(int elementNum, String stringPart, Image imagePart) Sets the element referenced by elementNum to the specified element, replacing the previous contents of the element.
void	setFitPolicy(int fitPolicy) Sets the application's preferred policy for fitting Choice element contents to the available screen space.
void	setFont(int elementNum, Font font) Sets the application's preferred font for rendering the specified element of this Choice.
void	setLabel(String label) Sets the label of the Item.
void	setLayout(int layout) Sets the layout directives for this item.
void	setSelectedFlags(boolean[] selectedArray) Attempts to set the selected state of every element in the ChoiceGroup.
void	setSelectedIndex(int elementNum, boolean selected) For ChoiceGroup objects of type MULTIPLE, this simply sets an individual element's selected state.
int	size() Gets the number of elements present.

Methods inherited from class javax.microedition.lcdui.Item

addCommand, getMinimumHeight, getMinimumWidth, getPreferredHeight, getPreferredWidth, notifyStateChanged, removeCommand, setDefaultCommand, setItemCommandListener, setPreferredSize

Methods inherited from class java.lang.Object

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

Constructor Detail

ChoiceGroup

public ChoiceGroup(String label,
                   int choiceType)

Creates a new, empty ChoiceGroup, specifying its title and its type. The type must be one of EXCLUSIVE or MULTIPLE. The IMPLICIT choice type is not allowed within a ChoiceGroup.

Parameters:

label - the item's label (see Item)

choiceType - either EXCLUSIVE or MULTIPLE

Throws:

IllegalArgumentException - if choice type is neither EXCLUSIVE nor MULTIPLE

See Also:

Choice.EXCLUSIVE, Choice.MULTIPLE, Choice.IMPLICIT

ChoiceGroup

public ChoiceGroup(String label,
                   int choiceType,
                   String[] stringElements,
                   Image[] imageElements)

Creates a new ChoiceGroup, specifying its title, the type of the ChoiceGroup, and an array of Strings and Images to be used as its initial contents.

The type must be one of EXCLUSIVE or MULTIPLE. The IMPLICIT type is not allowed for ChoiceGroup.

The stringElements array must be non-null and every array element must also be non-null. The length of the stringElements array determines the number of elements in the ChoiceGroup. The imageElements array may be null to indicate that the ChoiceGroup elements have no images. If the imageElements array is non-null, it must be the same length as the stringElements array. Individual elements of the imageElements array may be null in order to indicate the absence of an image for the corresponding ChoiceGroup element. Any elements present in the imageElements array must refer to immutable images.

Parameters:

label - the item's label (see Item)

choiceType - EXCLUSIVE or MULTIPLE

stringElements - set of strings specifying the string parts of the ChoiceGroup elements

imageElements - set of images specifying the image parts of the ChoiceGroup elements

Throws:

NullPointerException - if stringElements is null

NullPointerException - if the stringElements array contains any null elements

IllegalArgumentException - if the imageElements array is non-null and has a different length from the stringElements array

IllegalArgumentException - if choiceType is neither EXCLUSIVE nor MULTIPLE

IllegalArgumentException - if any image in the imageElements array is mutable

See Also:

Choice.EXCLUSIVE, Choice.MULTIPLE, Choice.IMPLICIT

Method Detail

setLabel

public void setLabel(String label)

Description copied from class: Item

Sets the label of the Item. If label is null, specifies that this item has no label.

Overrides:

setLabel in class Item

Parameters:

label - the label string

getLabel

public String getLabel()

Description copied from class: Item

Gets the label of this Item object.

Overrides:

getLabel in class Item

Returns:

the label string

setLayout

public void setLayout(int layout)

Description copied from class: Item

Sets the layout directives for this item.

It is illegal to call this method if this Item is contained within an Alert.

Overrides:

setLayout in class Item

Parameters:

layout - a combination of layout directive values for this item

See Also:

Item.getLayout()

Since:

BlackBerry API 4.2.1

getLayout

public int getLayout()

Description copied from class: Item

Gets the layout directives used for placing the item.

Overrides:

getLayout in class Item

Returns:

a combination of layout directive values

See Also:

Item.setLayout(int)

Since:

BlackBerry API 4.2.1

size

public int size()

Description copied from interface: Choice

Gets the number of elements present.

Specified by:

size in interface Choice

Returns:

the number of elements in the ChoiceGroup

getString

public String getString(int elementNum)

Description copied from interface: Choice

Gets the String part of the element referenced by elementNum. The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

getString in interface Choice

Parameters:

elementNum - the index of the element to be queried

Returns:

the string part of the element

Throws:

IndexOutOfBoundsException - if elementNum is invalid

See Also:

ChoiceGroup.getImage(int)

getImage

public Image getImage(int elementNum)

Description copied from interface: Choice

Gets the Image part of the element referenced by elementNum. The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

getImage in interface Choice

Parameters:

elementNum - the number of the element to be queried

Returns:

the image part of the element, or null if there is no image

Throws:

IndexOutOfBoundsException - if elementNum is invalid

See Also:

ChoiceGroup.getString(int)

append

public int append(String stringPart,
                  Image imagePart)

Description copied from interface: Choice

Appends an element to the Choice. The added element will be the last element of the Choice. The size of the Choice grows by one.

Specified by:

append in interface Choice

Parameters:

stringPart - the string part of the element to be added

imagePart - the image part of the element to be added, or null if there is no image part

Returns:

the assigned index of the element

Throws:

IllegalArgumentException - if the image is mutable

NullPointerException - if stringPart is null

insert

public void insert(int elementNum,
                   String stringElement,
                   Image imageElement)

Description copied from interface: Choice

Inserts an element into the Choice just prior to the element specified. The size of the Choice grows by one. The elementNum parameter must be within the range [0..size()], inclusive. The index of the last element is size()-1, and so there is actually no element whose index is size(). If this value is used for elementNum, the new element is inserted immediately after the last element. In this case, the effect is identical to append().

Specified by:

insert in interface Choice

Parameters:

elementNum - the index of the element where insertion is to occur

stringPart - the string part of the element to be inserted

imagePart - the image part of the element to be inserted, or null if there is no image part

Throws:

IndexOutOfBoundsException - if elementNum is invalid

IllegalArgumentException - if the image is mutable

NullPointerException - if stringPart is null

delete

public void delete(int elementNum)

Description copied from interface: Choice

Deletes the element referenced by elementNum. The size of the Choice shrinks by one. It is legal to delete all elements from a Choice. The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

delete in interface Choice

Parameters:

elementNum - the index of the element to be deleted

Throws:

IndexOutOfBoundsException - if elementNum is invalid

deleteAll

public void deleteAll()

Deletes all elements from this ChoiceGroup.

Specified by:

deleteAll in interface Choice

Since:

BlackBerry API 4.0.0

set

public void set(int elementNum,
                String stringPart,
                Image imagePart)

Description copied from interface: Choice

Sets the element referenced by elementNum to the specified element, replacing the previous contents of the element. The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

set in interface Choice

Parameters:

elementNum - the index of the element to be set

stringPart - the string part of the new element

imagePart - the image part of the element, or null if there is no image part

Throws:

IndexOutOfBoundsException - if elementNum is invalid

IllegalArgumentException - if the image is mutable

NullPointerException - if stringPart is null

isSelected

public boolean isSelected(int elementNum)

Description copied from interface: Choice

Gets a boolean value indicating whether this element is selected. The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

isSelected in interface Choice

Parameters:

elementNum - the index of the element to be queried

Returns:

selection state of the element

Throws:

IndexOutOfBoundsException - if elementNum is invalid

getSelectedIndex

public int getSelectedIndex()

Returns the index number of an element in the ChoiceGroup that is selected. For ChoiceGroup objects of type EXCLUSIVE there is at most one element selected, so this method is useful for determining the user's choice. Returns -1 if there are no elements in the ChoiceGroup.

For ChoiceGroup objects of type MULTIPLE, this always returns -1 because no single value can in general represent the state of such a ChoiceGroup. To get the complete state of a MULTIPLE Choice, see getSelectedFlags.

Specified by:

getSelectedIndex in interface Choice

Returns:

index of selected element, or -1 if none

getSelectedFlags

public int getSelectedFlags(boolean[] selectedArray_return)

Queries the state of a ChoiceGroup and returns the state of all elements in the boolean array selectedArray_return. NOTE: this is a result parameter. It must be at least as long as the size of the ChoiceGroup as returned by size(). If the array is longer, the extra elements are set to false.

For ChoiceGroup objects of type MULTIPLE, any number of elements may be selected and set to true in the result array. For ChoiceGroup objects of type EXCLUSIVE, exactly one element will be selected, unless there are zero elements in the ChoiceGroup.

Specified by:

getSelectedFlags in interface Choice

Parameters:

selectedArray_return - array to contain the results.

Returns:

the number of selected elements in the ChoiceGroup

Throws:

IllegalArgumentException - if selectedArray_return is shorter than the size of the ChoiceGroup.

NullPointerException - if selectedArray_return is null.

setSelectedIndex

public void setSelectedIndex(int elementNum,
                             boolean selected)

For ChoiceGroup objects of type MULTIPLE, this simply sets an individual element's selected state.

For ChoiceGroup objects of type EXCLUSIVE, this can be used only to select an element. That is, the selected parameter must be true . When an element is selected, the previously selected element is deselected. If selected is false , this call is ignored.

For both list types, the elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

setSelectedIndex in interface Choice

Parameters:

elementNum - the number of the element. Indexing of the elements is zero-based.

selected - the new state of the element true=selected, false=not selected.

Throws:

IndexOutOfBoundsException - if elementNum is invalid

setSelectedFlags

public void setSelectedFlags(boolean[] selectedArray)

Attempts to set the selected state of every element in the ChoiceGroup. The array must be at least as long as the size of the ChoiceGroup. If the array is longer, the additional values are ignored.

For ChoiceGroup objects of type MULTIPLE, this sets the selected state of every element in the Choice. An arbitrary number of elements may be selected.

For ChoiceGroup objects of type EXCLUSIVE, exactly one array element must have the value true. If no element is true, the first element in the Choice will be selected. If two or more elements are true, the implementation will choose the first true element and select it.

Specified by:

setSelectedFlags in interface Choice

Parameters:

selectedArray - an array in which the method collect the selection status

Throws:

IllegalArgumentException - if selectedArray is shorter than the size of the ChoiceGroup.

NullPointerException - if the selectedArray is null.

setFitPolicy

public void setFitPolicy(int fitPolicy)

Sets the application's preferred policy for fitting Choice element contents to the available screen space. The set policy applies for all elements of the Choice object. Valid values are Choice.TEXT_WRAP_DEFAULT, Choice.TEXT_WRAP_ON, and Choice.TEXT_WRAP_OFF. Fit policy is a hint, and the implementation may disregard the application's preferred policy.

RIM Implementation Notes

On BlackBerry devices, the implementation does disregard the application's preferred policy and always applies Choice.TEXT_WRAP_ON fit policy, so that text element contents is wrapped to multiple lines if necessary to fit available content space. The implementation disregards the application's preferred policy, conforming with the MIDP 2.1 specification that states for the method ChoiceGroup.setFitPolicy(int): "Fit policy is a hint, and the implementation may disregard the application's preferred policy."

Specified by:

setFitPolicy in interface Choice

Parameters:

fitPolicy - preferred content fit policy for choice elements

Throws:

IllegalArgumentException - if fitPolicy is invalid

See Also:

ChoiceGroup.getFitPolicy()

Since:

BlackBerry API 4.0.0, MIDP 2.0

getFitPolicy

public int getFitPolicy()

Gets the application's preferred policy for fitting Choice element contents to the available screen space. The value returned is the policy that had been set by the application, even if that value had been disregarded by the implementation.

Specified by:

getFitPolicy in interface Choice

Returns:

one of Choice.TEXT_WRAP_DEFAULT, Choice.TEXT_WRAP_ON, or Choice.TEXT_WRAP_OFF

See Also:

ChoiceGroup.setFitPolicy(int)

Since:

BlackBerry API 4.0.0, MIDP 2.0

setFont

public void setFont(int elementNum,
                    Font font)

Sets the application's preferred font for rendering the specified element of this Choice. An element's font is a hint, and the implementation may disregard the application's preferred font.

The elementNum parameter must be within the range [0..size()-1], inclusive.

The font parameter must be a valid Font object or null. If the font parameter is null, the implementation must use its default font to render the element.

Specified by:

setFont in interface Choice

Parameters:

elementNum - the index of the element, starting from zero

font - the preferred font to use to render the element

Throws:

IndexOutOfBoundsException - if elementNum is invalid

See Also:

ChoiceGroup.getFont(int)

Since:

BlackBerry API 4.0.0, MIDP 2.0

getFont

public Font getFont(int elementNum)

Gets the application's preferred font for rendering the specified element of this Choice. The value returned is the font that had been set by the application, even if that value had been disregarded by the implementation. If no font had been set by the application, or if the application explicitly set the font to null, the value is the default font chosen by the implementation.

The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

getFont in interface Choice

Parameters:

elementNum - the index of the element, starting from zero

Returns:

the preferred font to use to render the element

Throws:

IndexOutOfBoundsException - if elementNum is invalid

See Also:

ChoiceGroup.setFont(int elementNum, Font font)

Since:

BlackBerry API 4.0.0, MIDP 2.0