Java Reference
In-Depth Information
Introducing the TextField
For user input, the MIDP provides the
TextField
class.
TextField
s bear
input constraints
that can restrict user input in a variety of ways; for example, it may require that users
enter only numeric input or phone numbers. The
TextField
class can also format input in
a variety of ways and return only what is input; for example, it might show an entered
phone number as (831) 555-1212, yet report to the application that the entered number
was 8315551212. You set an input constraint using the
setConstraints
method with a flag
value such as
EMAILADDR
,
NUMERIC
,
PHONENUMBER
,
URL
, or
DECIMAL
. These can be accompanied
by additional flags (combined using the bitwise OR operator
|
) such as
PASSWORD
(which
keeps you from seeing the entered text) or
UNEDITABLE
.
The class also supports the notion of
input modes
, which let you provide hints to the
implementation regarding how numeric key presses should be mapped to alphanumeric
key presses. You set input modes by specifying the string name for an input mode to the
method
setInitialInputMode
; values include the name of Unicode character blocks as
defined by the Java SE class
java.lang.Character.UnicodeBlock
, which is preceded by the
string
UCB_
, as in the following:
•
UCB_BASIC_LATIN
for Latin languages
•
UCB_GREEK
for the Greek language
•
UCB_CYRILLIC
for Cyrillic languages
•
UCB_HEBREW
for Hebrew languages
•
UCB_ARABIC
for Arabic
•
UCB_THAI
for Thai
•
UCB_HIRAGANA
for Japanese Hiragana syllabary
•
UCB_KATAKANA
for Japanese Katakana syllabary
•
UCB_HANGUL_SYLLABLES
for Korean
The MIDP also defines the following specific input modes:
•
MIDP_UPPERCASE_LATIN
for the uppercase characters of Latin languages
•
MIDP_LOWERCASE_LATIN
for the lowercase characters of Latin languages
When creating a
TextField
, you pass to the constructor the label and default text,
followed by the maximum number of characters the
TextField
should permit the user to
enter, and finally the constraints (bitwise ORed as appropriate).
