Just An Application

December 15, 2009

What’s New In MIDP 3.0: Redux – LCDUI – Menus

Filed under: Java, JME, MIDP, MIDP3, MIDP3Issues, MIDP3LCDUI, Mobile Java — Tags: , , , , , — Simon Lewis @ 9:30 pm

Original Post

Changes Since Proposed Final Draft

The semantics of the depth returned by the method Menu.getMenuDepth() have been changed.

The method now

Returns this menu’s depth within its menu tree. The top menu is of depth 0, the menus attached to it are of depth 1, 2, etc. The top menu is the menu in the menu tree that has no parent menu . If a menu is attached to both a Displayable and another menu, its depth is calculated based on the menu to which it is attached. For instance, a menu A is a sub-menu of menu B and is also attached to a Displayable. If menu B is of depth 3, then menu A will return a depth of 4.

Previously, as I observed in my original post, the specification was both contradictory, and seemed to imply, amongst other things, that a Menu could effectively have two depths.

Issues

Although it is not a particularly serious issue, despite the changes, it is not exactly clear what having the ability to obtain the depth of a given Menu is actually for.

The depth of a Menu is only significant in the context of the maximum limit on Menu depth.

If you know that a Menu is at the maximum permitted depth then it is true that you know that you definitely cannot add a sub-Menu to it.

If you know that a Menu is not at the maximum permitted depth however, you do not know that you can add a given Menu as a sub-Menu with out knowing whether the Menu you wish to attach itself has any sub-Menus, and if so what the maximum depth of the sub-Menu tree, and you are going to have to compute that.

As I say it is not serious but some use-cases might have helped.

This is also true of the eternally enigmatic Menu.onParentEnabled(true). What is it for ?


Copyright (c) 2009 By Simon Lewis. All Rights Reserved.

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