Optimized For The Touch

The LWUIT developer guide generally recommends increasing the padding of components to make them "finger friendly" as a generic guide for LWUIT on touch devices. While this is true, its somewhat basic and we can do much more in LWUIT and outside of it to make our application easier for the touch...

Two of the newer features in LWUIT's SVN are touch menus and tactile feedback, both are off by default and should be explicitly activated. The reason for this is that we don't want to "enforce" our opinion on how touch should look/feel on an application.
You can query whether the device supports touch by invoking Display.getInstance().isTouchScreenDevice()

Notice that the isTouchScreenDevice() method doesn't work properly on some simulators... However, it seems to work reasonably well on the actual devices.

To enable touch menus just use:
UIManager.getInstance().getLookAndFeel().setTouchMenus(true);

You can customize the look of the buttons via the "TouchCommand" selector in the theme.

The tactile feedback causes the phone to vibrate when the user presses a component that is intractable (e.g. list/button). Since most touch screens aren't of very good quality this is very useful in giving the user a sense that the screen actually registered his interaction. To enable this you can use:
UIManager.getInstance().getLookAndFeel().setTactileTouchDuration(100);

The argument is the number of milliseconds to vibrate on touch 50 to 100 seem like reasonable numbers, 0 disables the feature.

Component now has isTactileTouch()/setTactileTouch(boolean) methods to toggle the tactile touch vibration per a specific component. By default LWUIT tries to initialize this based on focusability so for custom components it might be useful to manipulate this flag.

A somewhat older flag which we would recommend is fireOnClick() for Lists. By default lists require two clicks to activate an entry, the first selects the entry and the second opens it.
This allows "context command flow", e.g. a command such as "remove" that removes the current selected entry. However, on touch devices this sort of behavior is often inconvenient and you would expect the "remove" command to move you to a separate list of checkboxes to select the entries to remove.
You would normally expect a single tap on the entry to act like the fire key (send an action event immediately) and not like simple selection. Calling List.fireOnClick(true) makes the list behave like that which is more convenient for touch device, however you need to ensure your application flow can handle this.

There is also the virtual keyboard that Chen blogged about recently, this is immensely useful for touch and Chen has improved its performance considerably!

As a side note unrelated to LWUIT, many devices have a "compatibility" mode on by default where keys are placed by the device at the bottom of the touch screen to allow "none-touch" Java ME applications to run on the device. Applications are expected to explicitly declare their support for touch to utilize the full screen of the device. This is done using the following Jad flags:

Navi-Key-Hidden: true
Nokia-MIDlet-On-Screen-Keypad: no
MIDlet-Touch-Support: true

Notice that the last entry (MIDlet-Touch-Support) is required by current/older Samsung/LG devices but is illegal by the MIDP specification hence fails on Nokia etc. so for support on these devices you would need a copy of your JAD (only the jad) with this attribute added.

Update: LG  have added another JAD attribute required to hide the native vkb which you should probably add to all applications:
LGE-MIDlet-Display-Nav-Keypad: no