What are the characteristics of polymorphism in Java?

There are several features of polymorphism in Java.

1. One key aspect of polymorphism is that the compiled type of an object may not match its runtime type. In other words, a variable can be declared as one type at compile time but reference a different type of object at runtime.
2. Method overriding: Polymorphism allows subclasses to rewrite methods in the parent class. When a method that has been rewritten by the subclass is called, the method in the subclass will be executed instead of the method in the parent class.
3. Dynamic binding: Method calls in polymorphism are resolved at runtime rather than compile time. This means that when calling a polymorphic method, the method to be called will be determined based on the actual type of the object.
4. Enhance code flexibility and scalability: Polymorphism allows for more flexibility in the code, as one can reference and operate on objects of different subclasses through the parent class type. This way, when adding new subclasses, there is no need to modify existing code, only the parent class needs to be extended.
5. Polymorphism can achieve method parameter polymorphism: by using polymorphic parameters, method parameters can be declared as parent class types, thus accepting objects of any subclass type as parameters. This can improve code flexibility and reusability.

In conclusion, the characteristics of Java polymorphism include inconsistency between the compile-time type and the run-time type, method overrides, dynamic binding, flexibility and extensibility, and method parameter polymorphism.