MIDP GUI Development: Alert, List, Form, TextBox

MIDP
GUI
Development:

Alert,
List,
Form,
TextBox

Jussi
Pohjolainen

Tampere
University
of
Applied
Sciences

Displayable
Class
Hierarchy

javax.microedi-on.lcdui
javax.microedi-on.lcdui.game

Displayable
Canvas
GameCanvas

Screen

Alert
List
Form
TextBox

TextBox

•  To
get
the
user
input

•  TextBox a = new TextBox(String
title, String text, int maxSize,
int constraints)

Types
and
Flags

•  Types
•  Flags

–  TextField.ANY –  TextField.PASSWORD
–  TextField.NUMERIC –  TextField.UNEDITABLE
–  TextField.DECIMAL –  TextField.NON_PREDICTIVE
–  TextField.PHONENUMBER –  TextField.INITIAL_CAPS_WORD
–  TextField.
–  TextField.EMAILADDR
INITIAL_CAPS_SENTENCE
–  TextField.URL

TextBox
Usage

TextBox textbox =
new TextBox("Sähköposti",
"",
64,
TextField.EMAILADDR |
TextField.PASSWORD);

Alerts

•  There
are
two
types
of
alerts

–  Timed
Alert

•  Displayed
certain
amount
of
Ime

–  Modal
Alert

•  Demands
user
conﬁrmaIon

Modal
Alert

Alert
-‐
class

•  Constructor

–  public Alert(String title, String
alertText, Image alertImage,
AlertType alerttype);!
•  Methods

–  setTimeOut(...)!
–  setTimeOut(Alert.Forever)!
–  addCommand(...)!
•  AlertTypes

–  ALARM, CONFIRMATION, ERROR, INFO,
WARNING!

EXCLUSIVE,
MULTIPLE
and
IMPLICIT

ConstrucIng
Lists

•  When
you
create
a
list,
you
deﬁne
list's

–  type
(EXCLUSIVE,
MULTIPLE,
IMPLICIT)

–  Itle

–  string
elements
and
images
(voluntary)

•  API:

–  public List(String title, int type):
–  public List(String title, int type, String [] stringelements, Image
[] imageElements);

•  Scrolling
is
automaIcally
available

•  It
is
possibly
to
add
elements
to
the
list
with
append-
method.

List
Example
1

public class MyList extends MIDlet{
private List mList;
public MyList() {
mList = new List(”Wanna Buy?”, Choice.MULTIPLE);
mList.append(“Herring”, null);
mList.append(“Goose Liver”, null);
mList.append(“Jelly”, null);
}
public void startApp() {
Display.getDisplay(this).setCurrent(mList);
}
public void destroyApp(boolean unconditional) {}
public void pauseApp() {}
}

List
Example
2

public MyList() {
String [] elements =
{"hyytelöä", "kananmaksaa",
"ituja"};

mLista = new List("Haluatko
ostaa?", Choice.MULTIPLE,
elements, null);

}

Adding
and
Removing
List
elements

•  It
is
possible
to
add
and
remove
list
elements

•  The
elements
are
accessible
by
index
(0...n)

•  Replacing
a
element:
set(...)

•  Adding
element:
append(...)

•  Adding
element
to
a
certain
place:
insert(...)
•  Finding
element:
String getString(int n)
•  Removing
element:
void delete(int n)

MIDP
2.0
List

•  How
do
you
treat
the
elements,
if
they
don't

ﬁt
into
mobile
device's
screen?

–  setPolicy(...);

•  Choice.TEXT_WRAP_ON,
Choice.TEXT_WRAP_OFF,

Choice.TEXT_WRAP_DEFAULT

•  Changing
the
font:

–  setFont(...)

List
SelecIon

•  How
to
ﬁnd
out
what
element
user
selected?

–  public boolean isSelected(int i)!
–  public int getSelectedIndex()!
–  public void setSelectedIndex(int i, boolean s)!

•  See
ListExample.java

Intro
to
Form

•  Form
is
a
GUI-‐component
that
can
hold
other
GUI-‐
components

•  These
othe
GUI-‐components
are
called
items.

•  If
there
are
many
items,
the
form
will
provide

scrolling
mechanism.

•  Constructors:

–  public Form(String title)!
–  public Form(String title, Item[] items)!

Handling
Items

•  Adding
Items
to
the
Form:

–  Form a = new Form(“otsikko”);!
–  a.append(Item item);!
–  a.append(String str);!
–  a.append(Image image);!
•  Every
item
has
an
index:

–  a.set(int index, Item item)!
–  a.insert(int index, Item item)!
–  a.delete(int index)!
•  Other
methods:

–  int size();!
–  Item get(int index)!

Simple
Example

mForm = new Form("Otsikko");
mForm.append("moi");
mForm.append("hei");
mForm.append("tere");

Using
Items

•  There
are
many
items.

•  javax.microedition.lcdui.Item:!
–  ChoiceGroup!
–  CustomItem // We will look this..!
–  DateField!
–  Gauge!
–  ImageItem // .. and this later!
–  Spacer!
–  StringItem!
–  TextField!

Item
Layout

•  Every
Form
item
can
have
a
layout:

–  LAYOUT_LEFT!
–  LAYOUT_RIGHT!
–  LAYOUT_CENTER!
–  ...!
•  See
API!

Using
Item
Layout

StringItem layoutLeft = new StringItem("Layout: ", "LEFT");
layoutLeft.setLayout(Item.LAYOUT_LEFT);

StringItem layoutCenter = new StringItem("Layout: ", "CENTER");
layoutCenter.setLayout(Item.LAYOUT_CENTER);

StringItem layoutRight = new StringItem("Layout: ", "RIGHT");
layoutRight.setLayout(Item.LAYOUT_RIGHT);

mForm.append(layoutLeft);
mForm.append(layoutCenter);
mForm.append(layoutRight);

StringItem

•  Represents
a
simple
“Label”

Form form = new Form("Title");
StringItem st = new StringItem("Label: ";
"Value");
form.append(stringItem);

Item:
Spacer

•  Spacer
provides
empty
space
in
the
form.

–  Spacer empty = new Spacer(100,50); !

Item:
TextField

•  TextField:

–  public TextField
(String label,
String text, int
maxSize, int
constraints)!
•  Constraints
(same
as
in

TextBox)

–  ANY, NUMERIC,
DECIMAL,
PHONENUMBER,
EMAILADDR, URL!
–  PASSWORD, SENSITIVE;
UNEDITABLE...!

Item:
DateField

•  Date
and
Time
input.

–  public DateField(String label, int mode)!
–  public DateField(String label, int mode,
TimeZone timezone)!
•  mode

–  DATE, TIME, DATE_TIME!
•  Get
and
Set-‐methods:

–  public Date getDate()!
–  public void setDate()!

Item:
Gauge

•  Gauge
presents
integer
in
a
graphical
form.

–  public Gauge(String label, boolean interactive,
int maxValue, int initialValue)
•  By
using
parameter
interacIve
it
is
possible
to
deﬁne

can
the
user
modify
the
gauge.

•  IniIalValue
can
also
be:

•  CONTINUOUS_IDLE !
•  INCREMENTAL_IDLE !
•  CONTINUOUS_RUNNING !
•  INCREMENTAL_UPDATING !

Gauge
Images

Gauge kake1 = new Gauge("Editoitava", true, 100, 0);

Gauge kake2 = new Gauge("Ei-editoitava", false, 100,
50);

Gauge kake3 = new Gauge("INCREMENTAL_UPDATING",
false, Gauge.INDEFINITE,
Gauge.INCREMENTAL_UPDATING);
Gauge kake6 = new Gauge("CONTINUOUS_RUNNING",
false, Gauge.INDEFINITE,
Gauge.CONTINUOUS_RUNNING);

Item:
ChoiceGroup

•  Like
List

–  public ChoiceGroup(String label,
int choiceType, String []
elements, Image[] imageElements)!
•  Choicetype

–  EXCLUSIVE!
–  MULTIPLE!
–  MIDP 2.0: POPUP!

ChoiceGroup
Images

String [] lista = {"suomi", "ruotsi"};
ChoiceGroup choicegroup = new ChoiceGroup("Valitse
maa", Choice.POPUP, lista, null);

Items
and
Event
Handling

•  Instead
of
using
CommandListener
you
now

use
ItemStateListener.

•  Set
the
event
source
to
form
and
the
listener

has
to
implement
ItemStateListener
interface.

•  The
interface
has
only
one
method:

–  itemStateChanged(Item item)!
•  Example

MIDP GUI Development: Alert, List, Form, TextBox

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