Shulou(Shulou.com)06/03 Report--

Java object-oriented object-oriented concept and what are the three basic characteristics of object-oriented, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, hope you can gain something.

Object-oriented is referred to as OO (ObjectOriented). After 1980s, there has been the research of new system development methods, such as object-oriented analysis (OOA), object-oriented design (OOD), object-oriented programming (OOP) and so on.

For Java, everything is an object. Objects in the real world are abstractly embodied in the programming world, and an object represents a specific operation. Each object finally forms a complete program design, which can exist independently or inherit from other objects. The information is transmitted between objects through interaction to realize program development.

The concept of object

Java is an object-oriented programming language, and object is the core of object-oriented programming. The so-called object is the entity in the real world, and the object corresponds to the entity one by one, that is to say, every entity in the real world is an object, it is a kind of concrete concept. The object has the following characteristics:

Objects have properties and behaviors.

The object has a changing state.

The object is unique.

Objects are instances of a category.

Everything is an object, and everything in the real world can be regarded as an object.

For example, in real-world schools, there will be entities such as students and teachers, students have attributes such as student numbers, names, classes (data), and students also have operations such as learning, asking questions, eating and walking. Students are just abstract descriptions, and this abstract description is called "class". In the school activities are individual students, that is, Zhang, Li and so on. These specific individuals are called "objects", and "objects" are also called "examples".

Three core features of object-oriented

Object-oriented development mode is more helpful for people to open up their thinking, facilitate the division of programs in the specific development process, facilitate programmers to divide work and cooperation, and improve development efficiency. Object-oriented programming has the following advantages.

Reusability: code reuse, reduce the amount of code, improve development efficiency. The three core object-oriented features (inheritance, encapsulation, and polymorphism) described below all revolve around this core.

Scalability: means that new functions can be easily added to the system to facilitate software modification.

Manageability: the ability to combine functions with data for easy management.

The reason why this development mode makes programming more perfect and powerful is that object-oriented has three core features: inheritance, encapsulation and polymorphism.

Inheritance

Just as the children in life inherit all the property owned by their parents, the inheritance in the program means that the subclass has all the characteristics and behavior of the parent class, which is a relationship between classes. Java only supports single inheritance.

For example, if you define a Chinese teacher class and a math teacher class, if you do not use inheritance, then the properties and methods that need to be defined in the two classes

Many attributes and methods in the Chinese teacher class and the mathematics teacher class are the same. These same attributes and methods can be extracted and placed in a parent class, which is used to be inherited by the Chinese teacher class and the mathematics teacher class. Of course, the parent class can also inherit other types.

The main staff of the school is a large category, teachers and students are two subcategories of the main personnel of the school, and teachers can be divided into two sub-categories of Chinese teachers and math teachers, and students can also be divided into two sub-categories: monitor and group leader.

The purpose of using this hierarchical classification is to extract the common properties and methods of multiple classes and put them in their parent classes, and then only need to define their own unique properties and methods in the subclasses. and get their common properties and methods in the parent class in the form of inheritance.

Tip: C++ supports multiple inheritance, which means that a subclass can have more than one parent class. For example, a passenger ship is a ship and a means of transportation, and the parent class of a passenger ship is a ship and a means of transportation. Multi-inheritance can cause a lot of conflict problems, so many object-oriented languages do not support multi-inheritance. The Java language is single inherited, that is, there can be only one parent class, but Java can implement multiple interfaces (an interface is similar to a class, but its members do not have an executor. For more information, please refer to the "Java Interface" section), which can prevent conflicts caused by multiple inheritance.

Is it helpful for you to read the above content? If you want to know more about the relevant knowledge or read more related articles, please follow the industry information channel, thank you for your support.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.