Class Screen

  extended by javax.microedition.lcdui.Displayable
      extended by javax.microedition.lcdui.Screen
Direct Known Subclasses:
Alert, Form, List, TextBox

public abstract class Screen
extends Displayable

The common superclass of all high-level user interface classes. Adds optional title and ticker-tape output to the Displayable class. The contents displayed and their interaction with the user are defined by subclasses.

Using subclass-defined methods, the application may change the contents of a Screen object while it is shown to the user. If this occurs, and the Screen object is visible, the display will be updated automatically. That is, the implementation will refresh the display in a timely fashion without waiting for any further action by the application. For example, suppose a List object is currently displayed, and every element of the List is visible. If the application inserts a new element at the beginning of the List, it is displayed immediately, and the other elements will be rearranged appropriately. There is no need for the application to call another method to refresh the display.

It is recommended that applications change the contents of a Screen only while it is not visible (that is, while another Displayable is current). Changing the contents of a Screen while it is visible may result in performance problems on some devices, and it may also be confusing if the Screen's contents changes while the user is interacting with it.

In MIDP 2.0 the four Screen methods that defined read/write ticker and title properties were moved to Displayable, Screen's superclass. The semantics of these methods have not changed.

MIDP 1.0

Method Summary
Methods inherited from class javax.microedition.lcdui.Displayable
addCommand, getHeight, getTicker, getTitle, getWidth, isShown, removeCommand, setCommandListener, setTicker, setTitle, sizeChanged
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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