![]() To learn more about Class, visit Java Class (official Java documentation). obj.getSuperclass() - returns the super class of the class.obj.getModifiers() - returns the access modifier of the class.obj.getName() - returns the name of the class.Using the object, we are calling different methods of Class. Here, we are creating an object obj of Class using the getClass() method. Notice the statement, Class obj = d1.getClass() Here, we are trying to inspect the class Dog. In the above example, we have created a superclass: Animal and a subclass: Dog. String mod = Modifier.toString(modifier) put this class in different Dog.java file We can use this object to get information about the corresponding class at runtime.Įxample: Java Class Reflection import Now that we know how we can create objects of the Class. ![]() ![]() class extension // create an object of Class Here, we are using the object of the Dog class to create an object of Class.ģ. Using getClass() method // create an object of Dog class Here, the forName() method takes the name of the class to be reflected as its argument.Ģ. There exists three ways to create objects of Class:ġ. In order to reflect a Java class, we first need to create an object of Class.Īnd, using the object we can call various methods to get information about methods, fields, and constructors present in a class. The object of Class can be used to perform reflection. There is a class in Java named Class that keeps all the information about objects and classes at runtime. Sample code shows how to retrieve the component type for an array and how to set and get fields with array or enum types.In Java, reflection allows us to inspect and manipulate classes, interfaces, constructors, methods, and fields at run time. Arrays and Enumerated Types This lesson introduces two special types of classes: arrays, which are generated at runtime, and enum types, which define unique named object instances. Examples are provided for setting and getting field values, invoking methods, and creating new instances of objects using specific constructors. Members This lesson describes how to use the Reflection APIs to find the fields, methods, and constructors of a class. Classes This lesson shows the various ways to obtain aĬlass object and use it to examine properties of a class, including its declaration and contents. Each lesson contains code examples, tips, and troubleshooting information. This trail covers common uses of reflection for accessing and manipulating classes, fields, methods, and constructors. Reflective code breaks abstractions and therefore may change behavior with upgrades of the platform. Exposure of Internals Since reflection allows code to perform operations that would be illegal in non-reflective code, such as accessing private fields and methods, the use of reflection can result in unexpected side-effects, which may render code dysfunctional and may destroy portability. This is in an important consideration for code which has to run in a restricted security context, such as in an Applet. Security Restrictions Reflection requires a runtime permission which may not be present when running under a security manager. Consequently, reflective operations have slower performance than their non-reflective counterparts, and should be avoided in sections of code which are called frequently in performance-sensitive applications. Performance Overhead Because reflection involves types that are dynamically resolved, certain Java virtual machine optimizations can not be performed. The following concerns should be kept in mind when accessing code via reflection. If it is possible to perform an operation without using reflection, then it is preferable to avoid using it. Reflection is powerful, but should not be used indiscriminately. Test harnesses can make use of reflection to systematically call a discoverable set APIs defined on a class, to insure a high level of code coverage in a test suite. Debuggers and Test Tools Debuggers need to be able to examine private members on classes. Visual development environments can benefit from making use of type information available in reflection to aid the developer in writing correct code. Class Browsers and Visual Development Environments A class browser needs to be able to enumerate the members of classes. Extensibility Features An application may make use of external, user-defined classes by creating instances of extensibility objects using their fully-qualified names. With that caveat in mind, reflection is a powerful technique and can enable applications to perform operations which would otherwise be impossible. This is a relatively advanced feature and should be used only by developers who have a strong grasp of the fundamentals of the language. Reflection is commonly used by programs which require the ability to examine or modify the runtime behavior of applications running in the Java virtual machine.
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