Class reflection mechanism in Java

I. Concepts of reflection:
The concept of reflection was first proposed by Smith in 1982. It mainly refers to the ability of a program to access, detect, and modify its own state or behavior. The proposal of this concept soon led to research on application reflectivity in the computer science field. It was first adopted by the design field of programming language, and has made achievements in Lisp and object-oriented aspects. LEAD/LEAD ++, OpenC ++, MetaXa, and OpenJava are reflection-based languages. Recently, reflection mechanisms have been applied to Windows, operating systems, and file systems.
Reflection itself is not a new concept. It may remind us of the concept of reflection in optics. Although computer science has given a new meaning to the concept of reflection, in terms of phenomena, they do have some similarities that help us understand. In computer science, reflection is a type of application that can be self-described and self-controlled. That is to say, this type of application uses a mechanism to describe and monitor its own behavior, and according to its own behavior status and results, adjusts or modifies the status and semantics of the behavior described by the application. We can see that, compared with the general reflection concept, reflection in the computer science field not only refers to reflection itself, but also measures taken to reflect the results. All systems that adopt reflection mechanisms (I .e. reflection Systems) want to make their implementations more open. It can be said that all systems implementing reflection mechanisms are open, but open systems do not necessarily adopt reflection mechanisms. Openness is a necessary condition for reflection systems. In general, the reflection system must meet both the open conditions and the cause of connection (Causally-connected ). The so-called cause connection refers to the situation where the changes in the self-description of the reflection system can be immediately reflected in the actual status and behavior at the underlying level of the system, and vice versa. Open connection and cause connection are two basic elements of the reflection system. 13700863760
In Java, reflection is a powerful tool. It allows you to create flexible code that can be configured during running without the need for source representative links between components. Reflection allows us to enable our program code to access the internal information of classes loaded into the JVM when writing and executing, rather than the code for class collaboration selected in the source code. This makes reflection a major tool for building flexible applications. However, it should be noted that, if improperly used, reflection costs are high.
Ii. Class reflection in Java:
Reflection is one of the characteristics of the Java programming language. It allows running Java programs to check themselves, or "self-Review", and can directly operate on internal properties of the program. This capability of Java may not be used in many practical applications, but it does not exist in other programming languages. For example, Pascal, C, or C ++ cannot obtain information related to function definitions in the program.
1. Detection class:
1.1 reflection's Working Mechanism
The following simple example shows how reflection works.