J2ME in a Nutshell

Name

Command

Synopsis

Command is a class that represents an operation that the may be represented in the user interface. Commands may be added to any Displayable with the exception of Alerts and are rendered in a platform-dependent way, often using buttons or as entries in a menu system. When the user activates the user interface control associated with a Command, the CommandListener associated with the Displayable is notified.

A Command has three attributes that are set at construction time. Once set, the values of these attributes can be obtained using the getLabel(), getCommandType() and getPriority() methods, but cannot be changed:

Label

The command name that the user will see in the user interface.

Type

A constant value that indicates the semantic intent of the command.

Priority

An integer value that gives the priority of this command relative to others of the same type. Lower values indicate higher priority.

The type is used to indicate to the platform whether the command is one of the standard types that it knows about and might provide special display handling for, or an application-private command. The standard types, whose meanings should be obvious from their names, are BACK, CANCEL, EXIT, HELP, OK and STOP. Application-private commands are assigned types of ITEM or SCREEN.

The type usually determines where the platform will display the command. Where there is more than one command with the same type, the priority value is used to determine the relative prominence of each ...