Dev Dives: Streamline document processing with UiPath Studio Web
Intro to MIDP Development
1. MIDP
Development
Jussi
Pohjolainen
Tampere
University
of
Applied
Sciences
2. Class
Diagram
of
MIDP
app
abstract
class
MIDlet
+
int
checkPermission(String)
#
abstract
void
destroyApp(boolean)
+
String
getAppProperty(String)
+
void
noFfyDestroyed()
#
abstract
pauseApp()
+
boolean
plaGormRequest(String)
+
void
resumeRequest()
#
abstract
void
startApp();
class
MyMIDlet
3. Code
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.*;
public class MyMIDlet extends MIDlet {
public MyMIDlet() {}
public void startApp() {}
public void destroyApp(boolean unconditional) {}
public void pauseApp() {}
}
5. ApplicaFon
Manager
• Applica'on
Manager
controls
all
the
methods
in
the
previous
slide
• You
can
try
to
change
the
state
by
using
methods
like:
– void notifyDestroyed()
– notifyPaused()
– resumeRequest()
7. Intro
to
GUI
• Problem:
Mobile
Devices
are
totally
different
from
each
other
– Screen
size,
ResoluFon?
– Color
Depth?
– Input
Devices?
• Two
soluFons
– Abstrac'on:
Let
MIDP
take
care
of
the
pracFcal
implementaFon
– Discover:
Sniff
the
features
of
the
current
phone
and
act
according
to
them
8. AbstracFon
vs.
Discover
• AbstracFon:
Use
high-‐level
API
– Portability
key
issue
– Very
easy
to
use
– LiXle
control
over
look
and
feel
• Discover:
Use
low-‐level
API
– Full
control
over
graphics
– Classes
like
Canvas,
Graphics,
Image,
Font
– Time
consuming,
but
you
can
control
the
look
and
feel
9. Display
• MIDP
GUI
could
be
seen
as
a
deck
of
cards
• No
mulFple
windows
• Display is
a
class
that
represents
the
screen
display
• Display has
a
single
GUI-‐element
whose
content
is
controlled
by
one
app
at
any
Fme
• The
main
task
of
the
Display-‐class
is
to
take
care
of
what
is
visible
at
the
screen
10. Using
Display
–
class
in
Code
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class MyMIDlet extends MIDlet
{
public MyMIDlet() {}
public void pauseApp() {}
public void destroyApp(boolean ignore) {}
public void startApp()
{
Display d = Display.getDisplay(this);
d.setCurrent(…);
}
}
11. Using
Display
• You
ask
reference
to
the
client
device's
display:
public void startApp(){
Display d = Display.getDisplay(this)
}
• SpecificaFon
says
that
this
is
done
in
startApp-‐
method
• A^er
ge_ng
the
reference,
you
can
use
Display-‐
classes
methods:
– public void setCurrent(Displayable next)
– public void setCurrent(Alert alert, Displayable
nestDisplayable)
13. Displayable
• Display
is
responsible
for
changing
GUI
–
elements
on
the
screen
• These
GUI-‐elements
are
Displayable –
objects.
• Displayable is
a
abstract
class
that
has
couple
concrete
classes
17. DelegaFon
Event
Handling
• MIDlet's
event
handling
system
is
the
same
as
in
Java
SE
• DelegaFon
Event
Model:
– Simple
and
easy
to
learn
– Support
a
clean
separa'on
between
applica'on
and
GUI
code
– Facilitate
the
creaFon
of
robust
event
handling
code
which
is
less
error-‐prone
(strong
compile-‐Fme
checking)
– Flexible
enough
to
enable
varied
applicaFon
models
for
event
flow
and
propagaFon
– For
visual
tool
builders,
enable
run-‐Fme
discovery
of
both
events
that
a
component
generates
as
well
as
the
events
it
may
observe
– Support
backward
binary
compaFbility
with
the
old
model
19. DelegaFon
Event
Model
and
MIDlets
• In
MIDP,
event
source
is
usually
Displayable-‐
object
• RegistraFon
is
done
with
– setCommandListener(CommandListener l)
• Listener
can
be
any
object,
which
class
has
implemented
the
CommandListener
interface!
20. Example
• Event
source
– TextBox textbox = new TextBox(....);
• Event
Listener
– Cat listener = new Cat();
• RegistraFon
– textbox.setCommandListener(listener);
• The
Cat-‐class
must
implement
the
CommandListener-‐class.
• It
is
wise
to
add
some
commands
to
the
Textbox-‐screen:
– Command exitcommand = new Command(..);
– textbox.addCommand(exitcommand);
21. Listener
• Listener
can
be
any
class
that
implements
the
given
interface.
• In
this
case,
Listener
is
a
class
called
“Cat”
class Cat implements CommandListener{
public void commandAction(Command c,
Displayable d){
// This will be called
}
}
22. BL
and
GUI
in
the
same
class
• In
small
programs
it
is
usual
that
the
GUI
-‐
and
the
applicaFon
code
is
implemented
in
the
same
class.
• Now
the
listener
is
the
same
class:
– class OmaMIDlet extends MIDlet implements
CommandListener
• And
registraFon:
– textbox.setCommandListener(this);
