程式語言 - Java - J2ME - Hello, world!

Hello.java

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class Hello extends MIDlet {
    public void startApp() {
        Alert a = new Alert("main", "Hello, world!", null, AlertType.INFO);
        Display.getDisplay(this).setCurrent(a);
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }
}

manifest.mf

MIDlet-1: Hello, , Hello
MIDlet-Name: Hello
MIDlet-Version: 1.0
MIDlet-Vendor: You
MicroEdition-Profile: MIDP-2.0
MicroEdition-Configuration: CLDC-1.1

編譯、執行

$ javac -classpath midpapi20-2.0.4.jar Hello.java
$ jar cfm Hello.jar manifest.mf Hello.class
$ java -cp microemulator-swing-2.0.4.jar:microemulator-2.0.4.jar:midpapi20-2.0.4.jar org.microemu.app.Main Hello.jar