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 interface javax.microedition.lcdui.Choice

EXCLUSIVE, IMPLICIT, MULTIPLE

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 stringElement, Image imageElement) Appends an element to the Choice.
void	delete(int index) Deletes the element referenced by elementNum.
Image	getImage(int index) 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 index) Gets the String part of the element referenced by elementNum.
void	insert(int index, String stringElement, Image imageElement) Inserts an element into the Choice just before to the element specified.
boolean	isSelected(int index) Gets a boolean value indicating whether this element is selected.
void	set(int index, String stringElement, Image imageElement) Sets the element referenced by elementNum to the specified element, replacing the previous contents of the element.
void	setSelectedFlags(boolean[] selectedArray) Attempts to set the selected state of every element in the ChoiceGroup.
void	setSelectedIndex(int index, 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

getLabel, setLabel

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.

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

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 index)

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:

index - the index of the element to be queried

Returns:

the string part of the element

Throws:

IndexOutOfBoundsException - if index is invalid

See Also:

getImage(int)

getImage

public Image getImage(int index)

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:

index - 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 index is invalid

See Also:

getString(int)

append

public int append(String stringElement,
                  Image imageElement)

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:

stringElement - the string part of the element to be added

imageElement - 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 stringElement is null

insert

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

Description copied from interface: Choice

Inserts an element into the Choice just before to the element specified. The size of the Choice grows by one. The elementNum parameter must be within the range [0..size()-1], inclusive.

Specified by:

insert in interface Choice

Parameters:

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

stringElement - the string part of the element to be inserted

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

Throws:

IndexOutOfBoundsException - if index is invalid

IllegalArgumentException - if the image is mutable

NullPointerException - if stringElement is null

delete

public void delete(int index)

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:

index - the index of the element to be deleted

Throws:

IndexOutOfBoundsException - if index is invalid

set

public void set(int index,
                String stringElement,
                Image imageElement)

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:

index - the index of the element to be set

stringElement - the string part of the new element

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

Throws:

IndexOutOfBoundsException - if index is invalid

IllegalArgumentException - if the image is mutable

NullPointerException - if stringElement is null

isSelected

public boolean isSelected(int index)

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:

index - the index of the element to be queried

Returns:

selection state of the element

Throws:

IndexOutOfBoundsException - if index 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 index,
                             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 index parameter must be within the range [0..size()-1], inclusive.

Specified by:

setSelectedIndex in interface Choice

Parameters:

index - 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 index 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.