javax.microedition.lcdui
Class TextField

java.lang.Object
  |
  +--javax.microedition.lcdui.Item
        |
        +--javax.microedition.lcdui.TextField

public class TextField

extends Item

A TextField is an editable text component that may be placed into a Form. It can be given a piece of text that is used as the initial value.

A TextField has a maximum size, which is the maximum number of characters that can be stored in the object at any time (its capacity). This limit is enforced when the TextField instance is constructed, when the user is editing text within the TextField, as well as when the application program calls methods on the TextField that modify its contents. The maximum size is the maximum stored capacity and is unrelated to the number of characters that may be displayed at any given time. The number of characters displayed and their arrangement into rows and columns are determined by the device.

The implementation may place a boundary on the maximum size, and the maximum size actually assigned may be smaller than the application had requested. The value actually assigned will be reflected in the value returned by getMaxSize(). A defensively-written application should compare this value to the maximum size requested and be prepared to handle cases where they differ.

Input Constraints

The TextField shares the concept of input constraints with the TextBox class. The different constraints allow the application to request that the user's input be restricted in a variety of ways. The implementation is required to restrict the user's input as requested by the application. For example, if the application requests the NUMERIC constraint on a TextField, the implementation must allow only numeric characters to be entered.

The actual contents of the text object are set and modified by and are reported to the application through the TextBox and TextField APIs. The displayed contents may differ from the actual contents if the implementation has chosen to provide special formatting suitable for the text object's constraint setting. For example, a PHONENUMBER field might be displayed with digit separators and punctuation as appropriate for the phone number conventions in use, grouping the digits into country code, area code, prefix, etc. Any spaces or punctuation provided are not considered part of the text object's actual contents. For example, a text object with the PHONENUMBER constraint might display as follows:

     (408) 555-1212    

but the actual contents of the object visible to the application through the APIs would be the string "4085551212". The size method reflects the number of characters in the actual contents, not the number of characters that are displayed, so for this example the size method would return 10.

Some constraints, such as DECIMAL, require the implementation to perform syntactic validation of the contents of the text object. The syntax checking is performed on the actual contents of the text object, which may differ from the displayed contents as described above. Syntax checking is performed on the initial contents passed to the constructors, and it is also enforced for all method calls that affect the contents of the text object. The methods and constructors throw IllegalArgumentException if they would result in the contents of the text object not conforming to the required syntax.

The value passed to the setConstraints() method consists of a restrictive constraint setting described above, as well as a variety of flag bits that modify the behavior of text entry and display. The value of the restrictive constraint setting is in the low order 16 bits of the value, and it may be extracted by combining the constraint value with the CONSTRAINT_MASK constant using the bit-wise AND (&) operator. The restrictive constraint settings are as follows:

ANY
EMAILADDR
NUMERIC
PHONENUMBER
URL
DECIMAL


The modifier flags reside in the high order 16 bits of the constraint value, that is, those in the complement of the CONSTRAINT_MASK constant. The modifier flags may be tested individually by combining the constraint value with a modifier flag using the bit-wise AND (&) operator. The modifier flags are as follows:

PASSWORD
UNEDITABLE
SENSITIVE
NON_PREDICTIVE
INITIAL_CAPS_WORD
INITIAL_CAPS_SENTENCE


Input Modes

The TextField shares the concept of input modes with the TextBox class. The application can request that the implementation use a particular input mode when the user initiates editing of a TextField or TextBox. The input mode is a concept that exists within the user interface for text entry on a particular device. The application does not request an input mode directly, since the user interface for text entry is not standardized across devices. Instead, the application can request that the entry of certain characters be made convenient. It can do this by passing the name of a Unicode character subset to the setInitialInputMode() method. Calling this method requests that the implementation set the mode of the text entry user interface so that it is convenient for the user to enter characters in this subset. The application can also request that the input mode have certain behavioral characteristics by setting modifier flags in the constraints value.

The requested input mode should be used whenever the user initiates the editing of a TextBox or TextField object. If the user had changed input modes in a previous editing session, the application's requested input mode should take precedence over the previous input mode set by the user. However, the input mode is not restrictive, and the user is allowed to change the input mode at any time during editing. If editing is already in progress, calls to the setInitialInputMode method do not affect the current input mode, but instead take effect at the next time the user initiates editing of this text object.

The initial input mode is a hint to the implementation. If the implementation cannot provide an input mode that satisfies the application's request, it should use a default input mode.

The input mode that results from the application's request is not a restriction on the set of characters the user is allowed to enter. The user MUST be allowed to switch input modes to enter any character that is allowed within the current constraint setting. The constraint setting takes precedence over an input mode request, and the implementation may refuse to supply a particular input mode if it is inconsistent with the current constraint setting.

For example, if the current constraint is ANY, the call

    setInitialInputMode("MIDP_UPPERCASE_LATIN");    

should set the initial input mode to allow entry of uppercase Latin characters. This does not restrict input to these characters, and the user will be able to enter other characters by switching the input mode to allow entry of numerals or lowercase Latin letters. However, if the current constraint is NUMERIC, the implementation may ignore the request to set an initial input mode allowing MIDP_UPPERCASE_LATIN characters because these characters are not allowed in a TextField whose constraint is NUMERIC. In this case, the implementation may instead use an input mode that allows entry of numerals, since such an input mode is most appropriate for entry of data under the NUMERIC constraint.

A string is used to name the Unicode character subset passed as a parameter to the setInitialInputMode() method. String comparison is case sensitive.

Unicode character blocks can be named by adding the prefix "UCB_" to the the string names of fields representing Unicode character blocks as defined in the J2SE class java.lang.Character.UnicodeBlock. Any Unicode character block may be named in this fashion. For convenience, the most common Unicode character blocks are listed below.

UCB_BASIC_LATIN
UCB_GREEK
UCB_CYRILLIC
UCB_ARMENIAN
UCB_HEBREW
UCB_ARABIC
UCB_DEVANAGARI
UCB_BENGALI
UCB_THAI
UCB_HIRAGANA
UCB_KATAKANA
UCB_HANGUL_SYLLABLES


"Input subsets" as defined by the J2SE class java.awt.im.InputSubset may be named by adding the prefix "IS_" to the string names of fields representing input subsets as defined in that class. Any defined input subset may be used. For convenience, the names of the currently defined input subsets are listed below.

IS_FULLWIDTH_DIGITS
IS_FULLWIDTH_LATIN
IS_HALFWIDTH_KATAKANA
IS_HANJA
IS_KANJI
IS_LATIN
IS_LATIN_DIGITS
IS_SIMPLIFIED_HANZI
IS_TRADITIONAL_HANZI


MIDP has also defined the following character subsets:

MIDP_UPPERCASE_LATIN - the subset of IS_LATIN that corresponds to uppercase Latin letters

MIDP_LOWERCASE_LATIN - the subset of IS_LATIN that corresponds to lowercase Latin letters

Finally, implementation-specific character subsets may be named with strings that have a prefix of "X_". In order to avoid namespace conflicts, it is recommended that implementation-specific names include the name of the defining company or organization after the initial "X_" prefix.

For example, a Japanese language application might have a particular TextField that the application intends to be used primarily for input of words that are "loaned" from languages other than Japanese. The application might request an input mode facilitating Hiragana input by issuing the following method call:

    textfield.setInitialInputMode("UCB_HIRAGANA");       

Implementation Note

Implementations need not compile in all the strings listed above. Instead, they need only to compile in the strings that name Unicode character subsets that they support. If the subset name passed by the application does not match a known subset name, the request should simply be ignored without error, and a default input mode should be used. This lets implementations support this feature reasonably inexpensively. However, it has the consequence that the application cannot tell whether its request has been accepted, nor whether the Unicode character subset it has requested is actually a valid subset.

Since:

MIDP 1.0

Field Summary

static int	ANY ANY The user is allowed to enter any text.
static int	CONSTRAINT_MASK CONSTRAINT_MASK The mask value for determining the constraint mode.
static int	DECIMAL The user is allowed to enter numeric values with optional decimal fractions, for example "-123", "0.123", or ".5".
static int	EMAILADDR EMAILADDR The user is allowed to enter an e-mail address.
static int	INITIAL_CAPS_SENTENCE This flag is a hint to the implementation that during text editing, the initial letter of each sentence should be capitalized.
static int	INITIAL_CAPS_WORD This flag is a hint to the implementation that during text editing, the initial letter of each word should be capitalized.
static int	NON_PREDICTIVE Indicates that the text entered does not consist of words that are likely to be found in dictionaries typically used by predictive input schemes.
static int	NUMERIC NUMERIC The user is allowed to enter only an integer value.
static int	PASSWORD PASSWORD The text entered must be masked so that the characters typed are not visible.
static int	PHONENUMBER PHONENUMBER The user is allowed to enter a phone number.
static int	SENSITIVE Indicates that the text entered is sensitive data that the implementation must never store into a dictionary or table for use in predictive, auto-completing, or other accelerated input schemes.
static int	UNEDITABLE Indicates that editing is currently disallowed.
static int	URL URL The user is allowed to enter a URL.

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

Constructor Summary

TextField(String label, String text, int maxSize, int constraints)
Creates a new TextField object with the given label, initial contents, maximum size in characters, and constraints.

Method Summary

void	delete(int offset, int length) Deletes characters from the TextField.
int	getCaretPosition() Gets the current input position.
int	getChars(char[] data) Copies the contents of the TextField into a character array starting at index zero.
int	getConstraints() Get the current input constraints of the TextField.
int	getMaxSize() Returns the maximum size (number of characters) that can be stored in this TextField.
int	getMinimumHeight() Gets the minimum height of this TextField which is the height of the label
String	getString() Gets the contents of the TextField as a string value.
void	insert(char[] data, int offset, int length, int position) Inserts a subrange of an array of characters into the contents of the TextField.
void	insert(String src, int position) Inserts a string into the contents just prior to the character indicated by the position parameter, where zero specifies the first character of the contents of the TextField.
void	setChars(char[] data, int offset, int length) Sets the contents of the TextField from a character array, replacing the previous contents.
void	setConstraints(int constraints) Sets the input constraints of the TextField.
void	setInitialInputMode(String characterSubset) Sets a hint to the implementation as to the input mode that should be used when the user initiates editing of this TextField.
int	setMaxSize(int maxSize) Sets the maximum size (number of characters) that can be contained in this TextField.
void	setString(String text) Sets the contents of the TextField as a string value, replacing the previous contents.
int	size() Gets the number of characters that are currently stored in this TextField.

Methods inherited from class javax.microedition.lcdui.Item

addCommand, getLabel, getLayout, 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

Field Detail

ANY

public static final int ANY

ANY The user is allowed to enter any text.

Constant 0 is assigned to ANY.

See Also:

Constant Field Values

CONSTRAINT_MASK

public static final int CONSTRAINT_MASK

CONSTRAINT_MASK The mask value for determining the constraint mode. The application should use the logical AND operation with a value returned by getConstraints() and CONSTRAINT_MASK in order to retrieve the current constraint mode, in order to remove any modifier flags such as the PASSWORD flag.

Constant 0xFFFF is assigned to CONSTRAINT_MASK.

See Also:

Constant Field Values

DECIMAL

public static final int DECIMAL

The user is allowed to enter numeric values with optional decimal fractions, for example "-123", "0.123", or ".5".

The implementation may display a period "." or a comma "," for the decimal fraction separator, depending on the conventions in use on the device. Similarly, the implementation may display other device-specific characters as part of a decimal string, such as spaces or commas for digit separators. However, the only characters allowed in the actual contents of the text object are period ".", minus sign "-", and the decimal digits.

The actual contents of a DECIMAL text object may be empty. If the actual contents are not empty, they must conform to a subset of the syntax for a FloatingPointLiteral as defined by the Java Language Specification, section 3.10.2. This subset syntax is defined as follows: the actual contents must consist of an optional minus sign "-", followed by one or more whole-number decimal digits, followed by an optional fraction separator, followed by zero or more decimal fraction digits. The whole-number decimal digits may be omitted if the fraction separator and one or more decimal fraction digits are present.

The syntax defined above is also enforced whenever the application attempts to set or modify the contents of the text object by calling a constructor or a method.

Parsing this string value into a numeric value suitable for computation is the responsibility of the application. If the contents are not empty, the result can be parsed successfully by Double.valueOf and related methods if they are present in the runtime environment.

The sign and the fraction separator consume space in the text object. Applications should account for this when assigning a maximum size for the text object.

Constant 5 is assigned to DECIMAL.

Since:

MIDP 2.0

See Also:

Constant Field Values

EMAILADDR

public static final int EMAILADDR

EMAILADDR The user is allowed to enter an e-mail address.

Constant 1 is assigned to EMAILADDDR.

See Also:

Constant Field Values

INITIAL_CAPS_SENTENCE

public static final int INITIAL_CAPS_SENTENCE

This flag is a hint to the implementation that during text editing, the initial letter of each sentence should be capitalized. This hint should be honored only on devices for which automatic capitalization is appropriate and when the character set of the text being edited has the notion of upper case and lower case letters. The definition of sentence boundaries is implementation-specific.

If the application specifies both the INITIAL_CAPS_WORD and the INITIAL_CAPS_SENTENCE flags, INITIAL_CAPS_WORD behavior should be used.

The INITIAL_CAPS_SENTENCE modifier can be combined with other input constraints by using the bit-wise OR operator (|).

Constant 0x200000 is assigned to INITIAL_CAPS_SENTENCE.

Since:

MIDP 2.0

See Also:

Constant Field Values

INITIAL_CAPS_WORD

public static final int INITIAL_CAPS_WORD

This flag is a hint to the implementation that during text editing, the initial letter of each word should be capitalized. This hint should be honored only on devices for which automatic capitalization is appropriate and when the character set of the text being edited has the notion of upper case and lower case letters. The definition of word boundaries is implementation-specific.

If the application specifies both the INITIAL_CAPS_WORD and the INITIAL_CAPS_SENTENCE flags, INITIAL_CAPS_WORD behavior should be used.

The INITIAL_CAPS_WORD modifier can be combined with other input constraints by using the bit-wise OR operator (|).

Constant 0x100000 is assigned to INITIAL_CAPS_WORD.

Since:

MIDP 2.0

See Also:

Constant Field Values

NON_PREDICTIVE

public static final int NON_PREDICTIVE

Indicates that the text entered does not consist of words that are likely to be found in dictionaries typically used by predictive input schemes. If this bit is clear, the implementation is allowed to (but is not required to) use predictive input facilities. If this bit is set, the implementation should not use any predictive input facilities, but it instead should allow character-by-character text entry.

The NON_PREDICTIVE modifier can be combined with other input constraints by using the bit-wise OR operator (|).

Constant 0x80000 is assigned to NON_PREDICTIVE.

Since:

MIDP 2.0

See Also:

Constant Field Values

NUMERIC

public static final int NUMERIC

NUMERIC The user is allowed to enter only an integer value.

Constant 2 is assigned to NUMERIC.

See Also:

Constant Field Values

PASSWORD

public static final int PASSWORD

PASSWORD The text entered must be masked so that the characters typed are not visible. The actual contents of the text field are not affected, but each character is displayed using a mask character such as "*". The character chosen as the mask character is implementation-dependent. This is useful for entering confidential information such as passwords or PINs (personal identification numbers).

The PASSWORD modifier can be combined with any of the input constraints by using the logical OR operator (|). However, the PASSWORD modifier is nonsensical with some constraint values such as EMAILADDR, PHONENUMBER, and URL.

Constant 0x10000 is assigned to PASSWORD.

See Also:

Constant Field Values

PHONENUMBER

public static final int PHONENUMBER

PHONENUMBER The user is allowed to enter a phone number. The phone number is a special case, since a phone-based implementation may be linked to the native phone dialing application. The implementation may automatically start a phone dialer application that is initialized so that pressing the "green" key would be enough to make a call. The call must not made automatically without requiring user's confirmation.

Constant 3 is assigned to PHONENUMBER.

See Also:

Constant Field Values

SENSITIVE

public static final int SENSITIVE

Indicates that the text entered is sensitive data that the implementation must never store into a dictionary or table for use in predictive, auto-completing, or other accelerated input schemes. A credit card number is an example of sensitive data.

The SENSITIVE modifier can be combined with other input constraints by using the bit-wise OR operator (|).

Constant 0x40000 is assigned to SENSITIVE.

Since:

MIDP 2.0

See Also:

Constant Field Values

UNEDITABLE

public static final int UNEDITABLE

Indicates that editing is currently disallowed. When this flag is set, the implementation must prevent the user from changing the text contents of this object. The implementation should also provide a visual indication that the object's text cannot be edited. The intent of this flag is that this text object has the potential to be edited, and that there are circumstances where the application will clear this flag and allow the user to edit the contents.

The UNEDITABLE modifier can be combined with other input constraints by using the bit-wise OR operator (|).

Constant 0x20000 is assigned to UNEDITABLE.

Since:

MIDP 2.0

See Also:

Constant Field Values

URL

public static final int URL

URL The user is allowed to enter a URL.

Constant 4 is assigned to URL.

See Also:

Constant Field Values

Constructor Detail

TextField

public TextField(String label,
                 String text,
                 int maxSize,
                 int constraints)

Creates a new TextField object with the given label, initial contents, maximum size in characters, and constraints. If the text parameter is null, the TextField is created empty. The maxSize parameter must be greater than zero.

Parameters:

label - item label

text - the initial contents, or null if the TextField is to be empty

maxSize - the maximum capacity in characters

constraints - see input constraints

Throws:

IllegalArgumentException - if maxSize is zero or less

IllegalArgumentException - if the value of the constraints parameter is invalid

IllegalArgumentException - if text is illegal for the specified constraints

IllegalArgumentException - if the length of text exceeds the requested maximum capacity or the maximum capacity actually assigned

Method Detail

delete

public void delete(int offset,
                   int length)

Deletes characters from the TextField.

Parameters:

offset - the beginning of the region to be deleted

length - the number of characters to be deleted

Throws:

StringIndexOutOfBoundsException - if offset and length do not specify a valid range within the content of TextField

getCaretPosition

public int getCaretPosition()

Gets the current input position. For some UIs this may block some time and ask the user about the intended caret position, on some UIs may just return the caret position.

Returns:

the current caret position, 0 if in the beginning

getChars

public int getChars(char[] data)

Copies the contents of the TextField into a character array starting at index zero. Array elements beyond the characters copied are left unchanged.

Parameters:

data - the character array to receive the value

Returns:

the number of characters copied

Throws:

ArrayIndexOutOfBoundsException - if the array is too short for the contents

NullPointerException - if data is null

getConstraints

public int getConstraints()

Get the current input constraints of the TextField.

Returns:

the current constraints value

See Also:

constraints

getMaxSize

public int getMaxSize()

Returns the maximum size (number of characters) that can be stored in this TextField.

Returns:

the maximum size in characters

getString

public String getString()

Gets the contents of the TextField as a string value.

Returns:

the current contents

insert

public void insert(String src,
                   int position)

Inserts a string into the contents just prior to the character indicated by the position parameter, where zero specifies the first character of the contents of the TextField. If position is less than or equal to zero, the insertion occurs at the beginning of the contents, thus effecting a prepend operation. If position is greater than or equal to the current size of the contents, the insertion occurs immediately after the end of the contents, thus effecting an append operation. For example,text.insertString(s, text.size()) always appends the string s to the current contents.

The current size of the contents is increased by the number of inserted characters. The resulting string must fit within the current maximum capacity.

If the application needs to simulate typing of characters it can determine the location of the current insertion point ("caret") using the getCaretPosition() method. For example, text.insert(s, text.getCaretPosition()) inserts the string s at the current caret position.

Parameters:

src - the String to be inserted

position - the position at which insertion is to occur

Throws:

IllegalArgumentException - if the resulting contents are illegal for the current input constraints

IllegalArgumentException - if the insertion would exceed the current maximum capacity

NullPointerException - if src is null

insert

public void insert(char[] data,
                   int offset,
                   int length,
                   int position)

Inserts a subrange of an array of characters into the contents of the TextField. The offset and length parameters indicate the subrange of the data array to be used for insertion. Behavior is otherwise identical to insert().

Parameters:

data - the source of the character data

offset - the beginning of the region of characters to copy

length - the number of characters to copy

position - the position at which insertion is to occur

Throws:

ArrayIndexOutOfBoundsException - if offset and length do not specify a valid range within the data array

IllegalArgumentException - if the resulting contents are illegal for the current input constraints

IllegalArgumentException - if the insertion would exceed the current maximum capacity

NullPointerException - if data is null

setChars

public void setChars(char[] data,
                     int offset,
                     int length)

Sets the contents of the TextField from a character array, replacing the previous contents. Characters are copied from the region of the data array starting at array index offset and running for length characters. If the data array is null, the TextField is set to be empty and the other parameters are ignored.

Parameters:

data - the source of the character data

offset - the beginning of the region of characters to copy

length - the number of characters to copy

Throws:

ArrayIndexOutOfBoundsException - if offset and length do not specify a valid range within the data array

IllegalArgumentException - if the text is illegal for the current input constraints

IllegalArgumentException - if the text would exceed the current maximum capacity

setConstraints

public void setConstraints(int constraints)

Sets the input constraints of the TextField. If the the current contents of the TextField do not match the new constraints, the contents are set to empty.

Parameters:

constraints - see input constraints

Throws:

IllegalArgumentException - if constraints is not any of the ones specified in input constraints.

setInitialInputMode

public void setInitialInputMode(String characterSubset)

Sets a hint to the implementation as to the input mode that should be used when the user initiates editing of this TextField. The characterSubset parameter names a subset of Unicode characters that is used by the implementation to choose an initial input mode. If null is passed, the implementation should choose a default input mode.

See Input Modes for a full explanation of input modes.

Parameters:

characterSubset - a string naming a Unicode character subset, or null

Since:

MIDP 2.0

setMaxSize

public int setMaxSize(int maxSize)

Sets the maximum size (number of characters) that can be contained in this TextField. If the current contents of the TextField are larger than maxSize, the contents are truncated to fit.

Parameters:

maxSize - the new maximum size

Throws:

IllegalArgumentException - if maxSize is zero or less

setString

public void setString(String text)

Sets the contents of the TextField as a string value, replacing the previous contents.

Parameters:

text - the new value of the TextField

Throws:

IllegalArgumentException - if text is illegal for the current input constraints

IllegalArgumentException - if text would exceed the current maximum capacity

size

public int size()

Gets the number of characters that are currently stored in this TextField.

Returns:

number of characters in the TextField

getMinimumHeight

public int getMinimumHeight()

Gets the minimum height of this TextField which is the height of the label

Overrides:

getMinimumHeight in class Item

Returns:

the minimum height