(1. To generalize: To generalize is to neglect those aspects of a subject that are not relevant to the current program in order to pay fuller attention to the aspects related to the current program. Generalization does not mean to understand comprehensive problems, but only select a part of them, without some details for the time being. The generalization includes two aspects, one is the generalization of the process, and the other is the generalization of the data. 2. Inheritance: Inheritance is a hierarchical model of connecting classes, and allows and encourages the reuse of classes, it provides a clear way of expressing commonalities. A new class of the target can be derived from an existing class, a process called class inheritance. The new class inherits the characteristics of the original class, the new class is called the derived class (subclass) of the original class, and the original class is called the base class (parent class) of the new class. A derived class can inherit methods and instance variables from its base class, and the class can fix or add new methods to better suit specific needs. 3. Encapsulation: Encapsulation is to surround the process and data, and access to the data can only be done through a defined interface. Object-oriented computing begins with the fundamental concept that the real world can be represented as a set of fully autonomous, encapsulated objects that access other objects through a maintained interface. 4. Polymorphism: Polymorphism refers to permitting different classes of targets to respond to the same message. Polymorphism includes parametric polymorphism and inclusive polymorphism. Polymorphic language has the advantages of sensitivity, generality, behavior sharing, and code sharing, and it solves the problem of using program functions with the same name.
125 common java interview questions summary.doc)
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