How would you use an abstract class to implement the Template Method pattern, defining a fixed algorithm skeleton with some steps left abstract for subclasses to fill in?

An abstract class is particularly well-suited to the Template Method pattern (already covered in the design patterns topic) because, unlike an interface, it can provide a concrete, non-overridable (final) method defining the overall algorithm's fixed sequence, while declaring specific customization points as abstract methods that subclasses must implement -- an interface alone (even with default methods) can't achieve quite the same guarantee, since a default method CAN be overridden by an implementing class, potentially altering the intended algorithm sequence in a way a final template method in an abstract class specifically prevents.

public abstract class ReportGenerator {
    public final void generate() {  // fixed algorithm, cannot be overridden since it's final
        String data = fetchData();
        String formatted = formatData(data);
        saveReport(formatted);
    }
    protected abstract String fetchData();      // subclasses MUST implement
    protected abstract String formatData(String data);  // subclasses MUST implement
    protected void saveReport(String content) { System.out.println("Saving: " + content); }  // shared default behavior
}