Solution: Secure Banking Documents

abstract class Document {
    protected String owner;
    // Abstract classes have constructors to initialize their state
    public Document(String owner) {
        this.owner = owner;
    }
    // final ensures this logic cannot be tampered with
    public final void printOwner() {
        System.out.println("Document Owner: " + owner);
    }
    public abstract void printContent();
}
class PDFDocument extends Document {
    public PDFDocument(String owner) {
        // Must pass the owner to the parent constructor
        super(owner);
    }
    @Override
    public void printContent() {
        System.out.println("Decrypting PDF binary data...");
    }
}
class TextDocument extends Document {
    public TextDocument(String owner) {
        super(owner);
    }
    @Override
    public void printContent() {
        System.out.println("Reading text data...");
    }
}
public class Main {
    public static void main(String[] args) {
        Document pdf = new PDFDocument("Alice");
        Document txt = new TextDocument("Bob");
        pdf.printOwner(); 
        pdf.printContent();
        
        System.out.println("---");
        
        txt.printOwner();
        txt.printContent();
    }
}