Overriding vs Hiding: Static Methods, Fields and Private Methods

public class Hiding {
    public static void main(String[] args) {
        Base ref = new Derived();                       // the variable is a Base, the object is a Derived

        System.out.println(ref.instanceMethod());       // Derived  overridden: the object's real type decides
        System.out.println(ref.field);                  // Base     fields are never polymorphic
        System.out.println(Base.staticMethod());        // Base     static methods are hidden, not overridden
        System.out.println(Derived.staticMethod());     // Derived
        System.out.println(ref.callPrivate());          // Base     private methods are not inherited, so not overridden
    }
}

class Base {
    String field = "Base";
    String instanceMethod() { return "Base"; }
    static String staticMethod() { return "Base"; }
    private String secret() { return "Base"; }
    String callPrivate() { return secret(); }
}

class Derived extends Base {
    String field = "Derived";                           // hides the field
    @Override String instanceMethod() { return "Derived"; }
    static String staticMethod() { return "Derived"; }  // hides the static method
    private String secret() { return "Derived"; }       // a brand new method, not an override
}