From Forum Nokia Wiki

If we want to learn a new language, the first program is always the classical "Hello World!"

This program creates a new form with a string item and an exit button.

To install the tools needed for developing in Java ME for Nokia devices, see articles Getting started with Java ME, Installing Java ME development tools for S60, and Creating your first MIDlet using EclipseME.

package com.example.helloworld;
 
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.*;
 
public class HelloWorldMidlet extends MIDlet implements CommandListener {
 
    public HelloWorldMidlet() {
    }
    // Display
    private Display display;
    // Main form
    private Form form;
    // For the message
    private StringItem stringItem;
    // For the exit command
    private Command exitCommand;
 
    public void commandAction(Command command, Displayable displayable) {
        if (displayable == form) {
            if (command == exitCommand) {
                exitMIDlet();
            }
        }
    }
 
    public void startApp() {
        // Create form
        stringItem = new StringItem("Hello", "Hello World!");
        form = new Form(null, new Item[] {stringItem});
        exitCommand = new Command("Exit", Command.EXIT, 1);
        form.addCommand(exitCommand);
        form.setCommandListener(this);
 
        // Get display for drawning
        display = Display.getDisplay(this);        
        display.setCurrent(form);
    }
 
    // Your MIDlet should not call pauseApp(), only system will call this life-cycle method
    public void pauseApp() {
    }
 
    // Your MIDlet should not call destroyApp(), only system will call this life-cycle method    
    public void destroyApp(boolean unconditional) {
    }
 
    public void exitMIDlet() {
        display.setCurrent(null);
        notifyDestroyed();
    }
 
}