Assignment between Java Neutron class and base class variable

Assignment between Java Neutron class and base class variable

A subclass object can be assigned directly to a base class variable.

To assign a base class object to a subclass object variable, you must perform a type conversion,

Its syntax is:

Sub-class object variable = (subclass name) base class object name;

Nor can it be converted into chaos. If the type conversion fails, Java throws the following exception:

ClassCastException

Package Yanzheng;

class mammal{}

class Dog extends Mammal {}

class Cat extends mammal{}

Public class Testcast

{

Public Static void Main (String args[])

{

< /span>m

< /span>d new  dog ();

< /span>c new  cat ();

m = D ;

D=m;

D = (Dog) m ;

D=c;

C = (Cat) m ;

}

}

The first one: correct. Subclasses can assign values to base class objects.

Second: error. Cast m of parent class to subclass D

The third one: The fifth one refers to the conclusions from the beginning.

Fourth one: No. Although they all inherit from the same parent class, they are still two different subclasses, and two different subclasses cannot be assigned a value.

Assignment between Java Neutron class and base class variable