Getting Started: “Hello World” in J2ME

Whereas you write applications for the desktop and Applets for web browsers you write MIDlets for mobile devices.

Just as J2SE applications have an entry point (any class with a main() method) MIDlets have a class which extends the abstract MIDlet class. This class offers the startApp() method which will serve as the entry point to your MIDlet.

In J2SE, Hello World consists of merely System.out.println()-ing the static String “Hello World”. Unlike J2SE many J2ME devices do not have the concept of an on-screen console and as such we cannot avail ourselves of the System.out.println() method to print “Hello World” for us.

We must instead draw “Hello World” to a graphical canvas which we will then assign to be the currently displayed screen. If you’ve dabbled in AWT or Swing you likely have seen the Graphics object which acts as our paintbrush when painting to the Canvas. For those not familiar, the Graphics object is state-object with a current color, line-thickness, font etc…