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Java reflection tutorial update#
Java reflection tutorial code#

Test tools like Junit or Mockito use reflection in order to invoke desired methods containing specific syntax or to mock specific classes, interfaces and methods.

Java reflection tutorial code#

Debuggers use reflection to inspect dynamically the code that is being executed.

For example, IDEs like Eclipse or PHP Storm provide a mechanism to retrieve dynamically the arguments expected for a given method or a list of public methods starting by “get” for a given instance.

IDEs can heavily make use of reflection in order to provide solutions for auto completion features, dynamic typing, hierarchy structures, etc.

Here is a list with the most common use cases: In general, reflection can be used to observe and modify the behavior of a program at runtime.

Tools that automatically refactor or analyze the code may have trouble when a lot of reflection is present.ĭespite all the limitations, reflection is a very powerful tool in Java that can be taken into consideration in several scenarios.

The classes and methods are not directly exposed in the code and may vary dynamically so it can get difficult to change the number of parameters that a method expects if the code that calls this method is invoked via reflection. If your code uses reflection heavily it is going to be more difficult to maintain.

Another important disadvantage that is good to mention here is the maintenance of the code.

Security vulnerabilities have to be taken into consideration since the use of reflection may not be possible when running in secure contexts like Applets.

The performance is affected by the use of reflection since all compilation optimizations cannot be applied: reflection is resolved at runtime and not at compile stages.If some operation can be executed without using reflection, then we should not use it. Other important classes are Method, Field and Type containing specific reflection methods that we are going to see in this tutorial.Īlthough reflection is very useful in many scenarios, it should not be used for everything. The class Class contains all the reflection related methods that can be applied to classes and objects like the ones that allow a programmer to retrieve the class name, to retrieve the public methods of a class, etc. Reflection is present in Java since the beginning of the times via its reflection API. It is also possible to instantiate new classes, to create new instances and to execute their methods, all of it using reflection.

You do not need to know how classes or methods are called, neither the parameters that are needed, all of that can be retrieved at runtime using reflection. In Java, it is possible to inspect fields, classes, methods, annotations, interfaces, etc. Therefore, you will experience great in learning Java technology.Purely speaking, this example is not really reflection, because the code does not have to be analyzed at runtime and the task can be done in any other stage, but it can be also done at runtime and then we would be actually talking about reflection.Īnother example would be an application that analyzes the content of given classes and executes the methods that contain a specific annotation with arguments provided in runtime: In the Java Junit framework we have for example the annotation This is actually what Junit does and does it using reflection. Even if you have no prior knowledge of Java, you won’t face any difficulty understanding these tutorials.īecause we have covered each Java topic with real-time examples and programs in an easy way. I recommend you see these tutorials in the given order. Start from here, to learn Java programming. In each tutorial, you will also get interview questions and programming exercises to test your understanding. You can get an overview of the whole Core Java topics below with the link. If you are a beginner to learn Java programming, this may be the right platform.

Java reflection tutorial update#

We have taken great care not only to add a new tutorial but also thoroughly revise and update the existing content regularly so that you can get a better user experience. It will guide you step by step to learn every concept of the Java programming language. This core java tutorial is specially designed for beginners and experienced.