Lists and Forms - Beginning J2ME: From Novice to Professional - page 77

You can use null for the StringItem 's label or value to indicate that it should not be shown
on the screen. (Better yet, you could just use Form 's append(String) method.) StringItem inherits
setLabel() and getLabel() methods from Item . It also includes getText() and setText()
methods for accessing and adjusting the string value.
The appearance of both StringItem and ImageItem can be controlled using appearance
mode . The appearance mode allows the item to look like a URL link or a button, although in
all other respects the item behaves the same as a regular StringItem or ImageItem . The three
appearance modes (which are defined in the Item class) are as follows:
• PLAIN shows the item in its normal state.
• HYPERLINK shows the item as a URL. A typical action would be to attempt to open the link
using MIDlet 's platformRequest() method.
• BUTTON shows the item as a button. Note that this may be clumsy, especially on devices
without pointer events, and you should generally use a Command where you feel tempted
to use an item with a BUTTON appearance mode.
As with almost everything else in the javax.microedition.lcdui package, it's the imple-
mentation's responsibility to show different appearance modes, and your application may
look different on different devices. Furthermore, it is your application's responsibility to
implement appropriate behavior. For example, you might want to add a command to a
HYPERLINK StringItem that calls MIDlet 's platformRequest() method to open the link.
■ Note The J2ME Wireless Toolkit emulators don't show HYPERLINK or BUTTON StringItem s any differently
from PLAIN ones, except for one special case. If the StringItem has a BUTTON type and it has an associated
item command, it is shown with a beveled border.
Finally, there are also getFont() and setFont() methods in the StringItem class. We'll
describe the Font class in Chapter 13.
Spacer
Spacer represents empty space in a Form . Unlike other Item s, Spacer cannot gain focus and
cannot have commands. It may be used for layout purposes. All you need to do is specify a
minimum width and height:
public Spacer(minWidth, minHeight)
TextField
TextField represents an editable string. Figure 6-7 shows a TextField with a label of
“TextFieldTitle” and a value of “text”.
In Sun's MIDP emulator, text can be entered directly into a TextField either by clicking the
number buttons in the emulator or by typing on the keyboard. Of course, it's up to the imple-
mentation to decide exactly how to allow editing. Some implementations may even show a
separate screen for editing.