根据对象的投射类型访问阴影方法

Question

Method calls are always determined based on the runtime type of the object, however how can I call shadowed methods of base classes from an inherit instance?

class Base {
    String str = "base";
    String str() { return str; }
}

class Impl extends Base {
    String str = "impl";
    String str() { return str; }
}

class Test {
    public static void main(String[] args) {
        System.out.println(((Base) new Impl()).str);   // print 'base'
        System.out.println(((Base) new Impl()).str()); // print 'impl'
    }
}

For example above, how can I call the str() method of Base class from an Impl instance, preferably without using reflection?

Answer 1

Using the Keyword super

Accessing Superclass Members

If your method overrides one of its superclass's methods, you can invoke the overridden method through the use of the keyword super . You can also use super to refer to a hidden field (although hiding fields is discouraged). an example below.

public class Superclass {

    public void printMethod() {
        System.out.println("Printed in Superclass.");
    }
}

calling printMethod since child class

Here is a subclass, called Subclass, that overrides printMethod():

public class Subclass extends Superclass {

    // overrides printMethod in Superclass
    public void printMethod() {
        super.printMethod();
        System.out.println("Printed in Subclass");
    }
    public static void main(String[] args) {
        Subclass s = new Subclass();
        s.printMethod();    
    }
}

if you want to read more https://docs.oracle.com/javase/tutorial/java/IandI/super.html