hello_world.java

interface Printer {
    void print(Message message);
}

class Message {
    private String message;

    public Message(String message) {
        this.message = message;
    }

    public void print(Printer printer) {
        printer.print(this);
    }

    public String toString() {
        return message;
    }
}

abstract class AbstractPrinterFactory {
    public static AbstractPrinterFactory getFactory() {
        return new SystemOutPrinterFactory();
    }

    public abstract Printer getPrinter();
}

class SystemOutPrinterFactory extends AbstractPrinterFactory {
    public Printer getPrinter() {
        return new SystemOutPrinter();
    }
}

class SystemOutPrinter implements Printer {
    public void print(Message message) {
        System.out.println(message);
    }
}

class HelloWorld {
    public static void main(String[] args) {
        Message message = new Message("Hello, World!");
        AbstractPrinterFactory factory = SystemOutPrinterFactory.getFactory();
        Printer printer = factory.getPrinter();
        message.print(printer);
    }
}