abstract class in java

Static internal abstract classes can be inherited.public class Testfather {public static void Main (string[] args) {Person.talk2 a = new Newtalk ();A.get ();Person Person1 = new Student ("Alice", 20, "female");System.out.println (Person1.talk ());/* Person Person2 = new person (); *///abstract class cannot be called}}

Java basics 9-abstract class, java-AbstractJava basics 9-abstract class 1. Introduction to abstract classes /*Abstract class:Abstract: gener

Java Abstract class "instantiation", java Abstract Without doubt, abstract classes cannot be instantiated. abstract classes do not describe a specific thing as a specific

}9 }Ten classGoodstudentextendsstudent{ One //the abstract method must be implemented, otherwise the class is still an abstract class A Public voidStudy () { -SYSTEM.OUT.PRINTLN ("Good students do not study"); - } the } - Public classTest { - Public Static voidMain (string[] args) { -Goodstudent

Features of the Java abstract class:* Abstract classes cannot be instantiated* Subclass inherits Abstract class and instantiates subclass* Subclasses inherit abstract classes has penny

the method of the parent class, but the method name, parameter type, and number of arguments must be the same! Overrides of methods (overriding) and overloads (overloading) are different manifestations of Java polymorphism, which is a representation of polymorphism between parent class and subclass, and overloading is a representation of polymorphism in a class.

java– virtual functions, abstract functions, abstract classes, interfaces 1. Java virtual functions The existence of virtual functions is for polymorphism. C + + Ordinary member function plus virtual keyword becomes virtual function In Java, there is no concept of virtual

1. Java virtual functionsThe existence of virtual functions is for polymorphism.C + + the normal member function plus Virtual The keyword becomes a virtual functionjava c++ java java final keyword becomes non-virtual function PS: actually C + + and the Java The point of view in virtual function is similar.

Because both C + + and Java are object-oriented programming languages, their polymorphism is achieved by virtual functions and abstract functions, respectively.The virtual function of C + + can be overridden in subclasses, and the invocation is judged by the actual object, not by the pointer type (the invocation of the normal function is based on the current pointer type). A pure virtual function is a funct