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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Object | +--javax.microedition.lcdui.Displayable
An object that has the capability of being placed on the display. A
Displayable
object may have a title, a ticker,
zero or more commands and a listener associated with it. The
contents displayed and their interaction with the user are defined by
subclasses.
The title string may contain line breaks. The display of the title string must break accordingly. For example, if only a single line is available for a title and the string contains a line break then only the characters up to the line break are displayed.
Unless otherwise specified by a subclass, the default state of newly
created Displayable
objects is as follows:
Display
;Ticker
associated with this
Displayable
;null
;Commands
present; andCommandListener
present.
Method Summary | |
void |
addCommand(Command cmd)
Adds a command to the Displayable . |
int |
getHeight()
Gets the height in pixels of the displayable area available to the application. |
Ticker |
getTicker()
Gets the ticker used by this Displayable . |
String |
getTitle()
Gets the title of the Displayable . |
int |
getWidth()
Gets the width in pixels of the displayable area available to the application. |
boolean |
isShown()
Checks if the Displayable is actually visible
on the display. |
void |
removeCommand(Command cmd)
Removes a command from the Displayable . |
void |
setCommandListener(CommandListener l)
Sets a listener for Commands to this
Displayable ,
replacing any previous CommandListener . |
void |
setTicker(Ticker ticker)
Sets a ticker for use with this Displayable ,
replacing any
previous ticker. |
void |
setTitle(String s)
Sets the title of the Displayable . |
protected void |
sizeChanged(int w,
int h)
The implementation calls this method when the available area of the Displayable has been changed. |
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Method Detail |
public String getTitle()
Displayable
. Returns
null
if there is no title.null
if no titlesetTitle(java.lang.String)
public void setTitle(String s)
Displayable
. If
null
is given,
removes the title.
If the Displayable
is actually visible on
the display,
the implementation should update
the display as soon as it is feasible to do so.
The existence of a title may affect the size
of the area available for Displayable
content.
Addition, removal, or the setting of the title text at runtime
may dynamically change the size of the content area.
This is most important to be aware of when using the
Canvas
class.
If the available area does change, the application will be notified
via a call to sizeChanged()
.
s
- the new title, or null
for no titlegetTitle()
public Ticker getTicker()
Displayable
.null
if no
ticker is presentsetTicker(javax.microedition.lcdui.Ticker)
public void setTicker(Ticker ticker)
Displayable
,
replacing any
previous ticker.
If null
, removes the ticker object
from this Displayable
. The same ticker may be shared by
several Displayable
objects within an application. This is done by calling
setTicker()
with the same Ticker
object on several
different Displayable
objects.
If the Displayable
is actually visible on the display,
the implementation should update
the display as soon as it is feasible to do so.
The existence of a ticker may affect the size
of the area available for Displayable's
contents.
Addition, removal, or the setting of the ticker at runtime
may dynamically change the size of the content area.
This is most important to be aware of when using the
Canvas
class.
If the available area does change, the application will be notified
via a call to sizeChanged()
.
ticker
- the ticker object used on this screengetTicker()
public boolean isShown()
Displayable
is actually visible
on the display. In order
for a Displayable
to be visible, all of the
following must be true:
the Display's
MIDlet
must be
running in the foreground, the Displayable
must be the Display's
current screen, and the
Displayable
must not be
obscured by a
system screen.true
if the
Displayable
is currently visiblepublic void addCommand(Command cmd)
Displayable
. The
implementation may choose,
for example,
to add the command to any of the available soft buttons or place it
in a menu.
If the added command is already in the screen (tested by comparing the
object references), the method has no effect.
If the Displayable
is actually visible on the
display, and this call
affects the set of visible commands, the implementation should update
the display as soon as it is feasible to do so.cmd
- the command to be addedNullPointerException
- if cmd
is
null
public void removeCommand(Command cmd)
Displayable
.
If the command is not in the Displayable
(tested by comparing the
object references), the method has no effect.
If the Displayable
is actually visible on the
display, and this call
affects the set of visible commands, the implementation should update
the display as soon as it is feasible to do so.
If cmd
is null
, this method
does nothing.cmd
- the command to be removedpublic void setCommandListener(CommandListener l)
Commands
to this
Displayable
,
replacing any previous CommandListener
. A
null
reference is
allowed and has the effect of removing any existing listener.l
- the new listener, or null
.public int getWidth()
Displayable
subclass. This value may depend
on how the device uses the
display and may be affected by the presence of a title, a ticker, or
commands.
This method returns the proper result at all times, even if the
Displayable
object has not yet been shown.public int getHeight()
Displayable
subclass. This value may depend
on how the device uses the
display and may be affected by the presence of a title, a ticker, or
commands.
This method returns the proper result at all times, even if the
Displayable
object has not yet been shown.protected void sizeChanged(int w, int h)
Displayable
has been changed.
The "available area" is the area of the display that
may be occupied by
the application's contents, such as Items
in a
Form
or graphics within
a Canvas
. It does not include space occupied
by a title, a ticker,
command labels, scroll bars, system status area, etc. A size change
can occur as a result of the addition, removal, or changed contents of
any of these display features.
This method is called at least once before the
Displayable
is shown for the first time.
If the size of a Displayable
changes while
it is visible,
sizeChanged
will be called. If the size of a
Displayable
changes while it is not visible, calls to
sizeChanged
may be deferred. If the size had changed
while the Displayable
was not visible,
sizeChanged
will be
called at least once at the time the
Displayable
becomes visible once
again.
The default implementation of this method in Displayable
and its
subclasses defined in this specification must be empty.
This method is intended solely for being overridden by the
application. This method is defined on Displayable
even though applications are prohibited from creating
direct subclasses of Displayable
.
It is defined here so that applications can override it in
subclasses of Canvas
and Form
.
This is useful for Canvas
subclasses to tailor
their graphics and for Forms
to modify
Item
sizes and layout
directives in order to fit their contents within the the available
display area.
w
- the new width in pixels of the available areah
- the new height in pixels of the available area
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