![]() Debugging and Testing toolsĭebugging requires the ability to view internal details of a class which include its private members.Debugging and Testing tools may use reflection to make systematic invocations to the classes by use of reflection and ensure test case coverage. Using these, the visual development environments make the information of the classes readily available to the user so that they can write proper code. IDEs, especially those which are capable of visual development, such as Eclipse or Netbeans, and class browsers can make extensive use of Reflection. Using the concepts of reflection, a programmer can make use of externally available user-defined classes by creating instances of those extensible objects by using their fully qualified name Developing IDEs and Class Browsers Other than these, the class is one of the most important classes in use for Reflection as the objects of Class can store the actual information of the class that we want to investigate or reflect. Reflection is heavily used in Java frameworks such as Spring, Hibernate, Junit etc. Using the concept of Reflection, a programmer can now manipulate all attributes of a class – including its methods, constructors, and fields even at runtime, and even invoke methods of that class and get a complete snapshot of it. In Java, the process of analyzing, viewing and modifying all the internal attributes, behaviors and capabilities of a class at runtime is called Reflection. getFields() and getDeclaredFields() methods:.getConstructors() and getDeclaredConstructors() methods:.Exposure of Internal Fields and Attributes.Always remember! Whenever reflection is used, the security of the application is compromised. It is an advanced feature that should only be used by programmers or developers who have a good knowledge of the basics of the language. Conclusionīecause of the above-mentioned cons, it is generally advisable to avoid using reflection. Therefore, the operations performed by reflections are usually slow. Since the types in reflection are resolved dynamically, JVM (Java Virtual Machine) optimization cannot take place. For example, if one access the private members of a class and sets null value to it, then the other user of the same class can get the NullReferenceException, and this behaviour is not expected.Īnother demerit is the overhead in performance. Thus, reflection may leak important data to the outside world, which is dangerous. It is possible to access the private methods and fields of a class using reflection. It helps in the creation of Visual Development Environments and class browsers which provides aid to the developers to write the correct code.Ĭons: Using reflection, one can break the principles of encapsulation. It is also possible to call methods, instantiate a clear or to set the value of fields using reflection. Pros: Inspection of interfaces, classes, methods, and fields during runtime is possible using reflection, even without using their names during the compile time. While the reflection provides a lot of advantages, it has some disadvantages too. Java reflection should always be used with caution. Let's see the simple example of forName() method. It should be used if you know the fully qualified name of class.This cannot be used for primitive types. ![]() There are 3 ways to get the instance of Class class. Returns the total number of constructors of this class.ġ1) public Method getDeclaredMethod(String name,Class parameterTypes)throws NoSuchMethodException,SecurityException Returns the total number of methods of this class.ġ0) public Constructor getDeclaredConstructors()throws SecurityException Returns the total number of fields of this class.ĩ) public Method getDeclaredMethods()throws SecurityException Loads the class and returns the reference of Class class.ģ) public Object newInstance()throws InstantiationException,IllegalAccessExceptionĨ) public Field getDeclaredFields()throws SecurityException ![]() ![]() Commonly used methods of Class class: MethodĢ) public static Class forName(String className)throws ClassNotFoundException
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