Type patterns, `instanceof` operator, Java

InstanceofOperator.java

// without type patterns
if (obj instanceof String) { return ((String) s).length(); }

// type patterns, cast to String and assign to s
if (obj instanceof String s) { return s.length(); }

x instanceof String s && s.length()

// compile error, out of scope
x instanceof String s || s.length()

// refactor `area` method
...
    public double area(Object shape) throws NoSuchShapeException {
        if (shape instanceof Square s) return s.side * s.side;
        else if (shape instanceof Rectangle r) return r.height * r.width;
        else if (shape instanceof Circle c) return PI * c.radius * c.radius;
        throw new NoSuchShapeException();
    }
...