J2ME Display

• The devices display is seen as an instance of Display class in MIDP or CLDC profile.
•  The bit depth should be atlaest one. A bit depth of one can have 2 colors.Black and white. A bit  depth of 2 can have four and so on...So an n bit display willl allow 2^N colors.
• javax.microedition.lcdui and javax.microedition.lcdui.game packages manage the display.
  
• Contents of display are changed by passing Displayable() instances to setCurrent() method of Display.
• public void startApp() {
  Display d = Display.getDisplay(this);
  // ...
  } // this is a typical program to start Display in the startApp() method.

J2ME - Configurations and Profiles

In general, the whole J2ME can be divided into two. Configurations and Profiles.

Configurations are the a set of specifications defined for a kind of device whose constrains are memory and processing capability. CDC(Connected Device Configuration) and CLDC(Connected Limited Device Configuration). Usually a minimum and maximum amount of memory elements like ROM or RAM is specified as configuration.

The term Profile is more specific. A family of devices which come under a particular category in a "Device" is called a profile. It is build on top of a configuration. It specifies a set of APIs for the application development of that family. MIDP or Mobile Information Device Profile is the example. MIDP comes under CLDC. It specifies additional memory constrains, screen size, network connection and input mode which are not specified by CLDC.