#JAVA REFLECTION TUTORIAL HOW TO#
#JAVA REFLECTION TUTORIAL FOR ANDROID#
#JAVA REFLECTION TUTORIAL ANDROID#

not int, but Integer) by name dynamically at runtime, instead of at compile time: You can also use the Class method called forName() to load a non-primitive class (e.g. Within this class, you’ll find many methods for inspecting different aspects of a class, such as its fields, constructors, methods, permissions, and more. This class provides the starting point for all reflection APIs. Java classes are represented at runtime using the Class () class. This allows the developer to leverage new APIs where available while still supporting the older devices-all in the same application.

#JAVA REFLECTION TUTORIAL ANDROID#

To do this, Android developers may use reflection techniques to determine, at runtime, if a specific class or method is available before trying to use it. However, Android developers often want to target devices running different versions of Android with a simple application package. are added, updated, and (less frequently) removed. So what does this have to do with Android development? Well, with each new version of the Android SDK, classes, interfaces, methods, etc. The Java Reflection APIs are available as part of the package, which is included within the Android SDK for developers to use. use of public, protected, private), you can then construct objects, access fields, and invoke methods dynamically. Within the security constraints imposed by Java (e.g. Reflection gives developers the flexibility to inspect and determine API characteristics at runtime, instead of compile time.

#JAVA REFLECTION TUTORIAL HOW TO#

It’s freely available for Windows, Mac, and Linux operating systems.įor complete instructions on how to install Eclipse (including which versions are supported) and the Android SDK, see the Android developer website.

#JAVA REFLECTION TUTORIAL FOR ANDROID#

Eclipse is a very popular development environment (IDE) for Java and the preferred IDE for Android development. To develop Android applications (or any Java applications, for that matter), you need a development environment to write and build applications. Technically, you don’t need any tools to complete this tutorial but you will certainly need them to develop Android applications. In this tutorial, you’ll learn the basics of Java reflection, including how to inspect the methods and fields of a given class, check for the availability of specific methods, and other practical tasks you may need to use when developing for different versions of the Android SDK. Using reflection, it can quickly dynamically initialize the classes required.In this tutorial, you’ll become familiar with the concept of Java reflection: the ability of a class or object to examine details about its own implementation programmatically.Īndroid applications are written in the Java, a programming language that supports reflection-the ability of an object to examine itself. (Here is a set of examples of how to use JUnit.)įor web frameworks, product developers define their own implementation of interfaces and classes and put is in the configuration files. Reflection is the common approach of famework.įor example, JUnit use reflection to look through methods tagged with the annotation, and then call those methods when running the unit test.

Change accessibility flag of Constructor, Method and Field.Invoke any method of an object at runtime.Examine a class's field and method at runtime.Construct an object for a class at runtime.There are some APIs to change accessibilities of methods and fields, but not structures.

In Java, reflection is more about introspection, because you can not change structure of an object. Method m = c.getDeclaredMethod('bark', new Class)

Java reflection tutorial