Explain the principle of dynamic routing of method calls in object-oriented programming.

Dynamic dispatch of method calls is a mechanism in object-oriented programming that determines which specific method implementation to invoke based on the actual type of the object at runtime, rather than at compile time.

In Java, this is achieved through virtual methods: if a method is declared in a base class and overridden in a subclass, then when called through a reference of the base type, the version of the method corresponding to the actual type of the object will be invoked.

Example:

class Animal {
    void sound() {
        System.out.println("Some sound");
    }
}

class Dog extends Animal {
    @Override
    void sound() {
        System.out.println("Bark");
    }
}

Animal a = new Dog();
a.sound(); // Will print "Bark", even though the variable type is Animal

Thus, dynamic dispatch allows for polymorphism, making program behavior flexible and extensible.

Under the hood, the JVM uses virtual method tables (vtables) for quick determination of the correct implementation at runtime.