java语言的三大特性即是封装、继承、多态（The three main features of Java language are encapsulation, inheritance, polymorphism）.docVIP

java语言的三大特性即是封装、继承、多态（The three main features of Java language are encapsulation, inheritance, polymorphism） The three main features of Java language are encapsulation, inheritance, polymorphism First, simply define the 3 major features: Encapsulation: hides the properties and implementation details of the object. It only interfaces to the public and controls the access level of the read and modify attributes in the program. Abstract the data and behavior (or function) combine to form an organic whole, which is the data and operation data of the source code for the organic combination of the formation of class, in which data and function are members of the class. The purpose of encapsulation is to enhance security and simplify programming. Users do not have to understand specific implementation details, but use the class members through an external interface and a specific access permission. The basic requirement of encapsulation is to privatize all attributes and provide getter and setter methods for each property. If there is a constructor with a reference, write a constructor without arguments. When you are developing, you often have to test classes that have already been written, so there are times when you override the toString method, but this is not necessary. Inheritance: code reuse through inheritance. All classes in Java are derived by directly or indirectly inheriting the java.lang.Object class. The inherited class is called a subclass is an inherited class called the parent class. Subclasses cannot inherit member variables and methods that access permissions to private in the parent class. Subclasses can override the methods of the parent class and name member variables that are the same as the parent class. However, Java does not support multiple inheritance, that is, the ability of a class to derive from multiple superclass. Minimizing inheritance in development is done to reduce the coupling of the program. Polymorphism: polymorphism is divided into t