Limited Connected Device User Interface (LCDUI) is the base of any Graphical User Interface (GUI) created in Java™ ME. It has a similar role to the Abstract Windowing Toolkit (AWT) and Swing APIs, which are used in Java SE and Java EE but offers a more restricted and resource-efficient approach to UI development.
LCDUI has a simple screen-based approach where a single Displayable is always active at a time in the display
area of the application user interface. This Displayable can contain predefined screen elements, or be manipulated in more
specific ways.
The high-level APIs are designed for applications that have client
parts that run on mobile devices. For these applications, portability
across devices is important. To achieve this portability, the high-level
components employ a high level of abstraction and that provides a
pre-defined look and feel. Generally high-level MIDlets employ common
components with clearly defined features and most low-level applications
feature some high-level parts, such as a main menu created with a List object.
All high-level APIs are derived from the Screen superclass. When a MIDlet utilises these classes, the actual implementation
takes care of aspects such as drawing, fonts, and navigation. In other
words, every Screen object provides presentation
and layout for itself and MIDP applications that use high-level APIs
define only the content. Screen classes map directly
to native Series 40 and New Nokia
Asha UI on Nokia Asha software platform 1.0 controls.
The following table lists the line separators and the corresponding new line character combinations supported by LCDUI.
Line separator |
New line escape in Java code |
Unicode value |
|---|---|---|
CR (Carriage Return) |
|
U+000D |
CRLF (Carriage Return + Line Feed) |
|
U+000D, U+000A |
LF (Line Feed) |
|
U+000A |
LS (Line Separator, only in Unicode) |
|
U+2028 |
As a rule, each new line character combination results
in exactly one forced line break when used in a String or character array that is displayed on the screen by a UI element.
However, there are some exceptions when a new line character combination
is not displayed as line break. The following sections describe these
exceptions.
In a Command label, each new line
character combination is displayed as a box glyph (an empty rectangle).
If there is only one line available for the title of a Displayable, any new line character combinations are displayed
as white spaces (U+0020). If there are multiple lines available for
the title, each new line character combinations forces a line break,
unless the new line character combination is on the last available
line, in which case it is displayed as a white space.
If the fit policy of a ChoiceGroup or List is set to TEXT_WRAP_ON, each new line character combination in an element forces a line
break in the displayed text. If the fit policy is set to TEXT_WRAP_OFF, the element text is limited to a single line and cropped if necessary.
If the text contains a new line character combination in the first
line, the text is cropped from the new line character combination
onwards. The cropping is indicated by an ellipsis ("...").
In a Ticker, each new line character combination
is displayed as a white space on Series 40 devices.