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.

Since:

MIDP 1.0

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 ChoiceGroup.
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.
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 stringPart, Image imagePart) Inserts an element into the ChoiceGroup 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 String and Image parts of the element referenced by elementNum, 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	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() Returns the number of elements in the ChoiceGroup.

Methods inherited from class javax.microedition.lcdui.Item

addCommand, getLabel, getLayout, getMinimumHeight, getMinimumWidth, getPreferredHeight, getPreferredWidth, notifyStateChanged, removeCommand, setDefaultCommand, setItemCommandListener, setLabel, setLayout, 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, MULTIPLE, or POPUP. The IMPLICIT choice type is not allowed within a ChoiceGroup.

Parameters:

label - the item's label (see Item)

choiceType - EXCLUSIVE, MULTIPLE, or POPUP

Throws:

IllegalArgumentException - if choiceType is not one of EXCLUSIVE, MULTIPLE, or POPUP

See Also:

Choice.EXCLUSIVE, Choice.MULTIPLE, Choice.IMPLICIT, Choice.POPUP

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, MULTIPLE, or POPUP. 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. Non-null elements of the imageElements array may refer to mutable or immutable images.

Parameters:

label - the item's label (see Item)

choiceType - EXCLUSIVE, MULTIPLE, or POPUP

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 not one of EXCLUSIVE, MULTIPLE, or POPUP

See Also:

Choice.EXCLUSIVE, Choice.MULTIPLE, Choice.IMPLICIT, Choice.POPUP

Method Detail

size

public int size()

Returns the number of elements in the ChoiceGroup.

Specified by:

size in interface Choice

Returns:

the number of elements in the ChoiceGroup

getString

public String getString(int elementNum)

Gets the String part of the element referenced by elementNum.

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:

getImage(int)

getImage

public Image getImage(int elementNum)

Gets the Image part of the element referenced by elementNum.

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:

getString(int)

append

public int append(String stringPart,
                  Image imagePart)

Appends an element to the ChoiceGroup.

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:

NullPointerException - if stringPart is null

insert

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

Inserts an element into the ChoiceGroup just prior to the element specified.

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

NullPointerException - if stringPart is null

delete

public void delete(int elementNum)

Deletes the element referenced by elementNum.

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

set

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

Sets the String and Image parts of the element referenced by elementNum, replacing the previous contents of the element.

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

NullPointerException - if stringPart is null

isSelected

public boolean isSelected(int elementNum)

Gets a boolean value indicating whether this element is selected.

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 and POPUP 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

See Also:

setSelectedIndex(int, boolean)

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 and POPUP 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

See Also:

setSelectedFlags(boolean[])

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 and POPUP, 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

See Also:

getSelectedIndex()

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 and POPUP, 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

See Also:

getSelectedFlags(boolean[])

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.

Specified by:

setFitPolicy in interface Choice

Parameters:

fitPolicy - preferred content fit policy for choice elements

Throws:

IllegalArgumentException - if fitPolicy is invalid

Since:

MIDP 2.0

See Also:

getFitPolicy()

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

Since:

MIDP 2.0

See Also:

setFitPolicy(int)

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

Since:

MIDP 2.0

See Also:

getFont(int)

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

Since:

MIDP 2.0

See Also:

setFont(int elementNum, Font font)