Lists and Forms - Beginning J2ME: From Novice to Professional - page 69

public String getString(int elementNum)
public Image getImage(int elementNum)
public void delete(int elementNum)
public void deleteAll()
The deleteAll() method removes every element from the List .
Finally, the size() method returns the number of elements in the List .
Although you usually give the MIDP implementation the responsibility of displaying your
List , methods in List give you some control over the appearance of a List . The first method,
setFitPolicy() , tells the List how it should handle elements whose text is wider than the screen.
The possible values (from the Choice interface) are the following:
• TEXT_WRAP_ON denotes that long elements will be wrapped to multiple lines.
• TEXT_WRAP_OFF denotes that long elements will be truncated at the edge of the screen.
• TEXT_WRAP_DEFAULT indicates that the implementation should use its default fit policy.
Another new method is setFont() , which allows you to specify the font that will be used for
a specific List element. (Fonts will be fully discussed in Chapter 13.) The current Font for an
element can be retrieved by calling getFont() . Calls to setFitPolicy() and setFont() only
serve as hints; it's up to the implementation to decide how to display the List and whether the
requested fit policy or font can be honored.
Working with List Selections
You can find out whether a particular element in a List is selected by supplying the element's
index to the following method:
public boolean isSelected(int index)
For EXCLUSIVE and IMPLICIT lists, the index of the single selected element is returned from
the following method:
public int getSelectedIndex()
If you call getSelectedIndex() on a MULTIPLE list, it will return -1 .
To change the current selection programmatically, use setSelectedIndex() .
public void setSelectedIndex(int index, boolean selected)
Finally, List allows you to set or get the selection state en masse with the following methods.
The supplied arrays must have as many array elements as there are list elements.
public int getSelectedFlags(boolean[] selectedArray_return)
public void setSelectedFlags(boolean[] selectedArray)
An Example
The example in Listing 6-1 shows a simple MIDlet that could be part of a travel reservation
application. The user chooses what type of reservation to make. This example uses an IMPLICIT
list, which is essentially a menu.