jhgasil.blogg.se - Java reflection tutorial for beginners

#JAVA REFLECTION TUTORIAL FOR BEGINNERS HOW TO#
#JAVA REFLECTION TUTORIAL FOR BEGINNERS CODE#

Reflection API provides us information about the class to which an object belongs and also the members of that class which can be accessed by using the object.Java Reflection API uses two packages namely java.lang and to introspect and modify the runtime behavior of a Java application during runtime.Static void method1() throws ClassNotFoundException ) Technique 1: Using forName() method of Class class

TestReflection.java package techguru.examples At the same time we would also like to determine if the specified Classobject represents an interface type or class type by using isInterface() method of.

#JAVA REFLECTION TUTORIAL FOR BEGINNERS HOW TO#

The following example demonstrates how to get the instance of Classclass in different ways. NOTE:The getClass() method of is an important method which returns the runtime class of an object and its return type is Class. In addition to these methods, the classes in the package also have some useful methods for performing introspection and analysis. getField(), getFields(), getDeclaredFields().getMethod(), getMethods(), getDeclaredMethods().getConstructor(), getConstructors(), getDeclaredConstructor().To these three useful methods the Reflection API adds some additional methods to class Class. newInstance(), which invokes the null constructor on the class (if it exists) and returns us an object instance of that class of object.GetName(), which returns the name of the class as a Stringobject, which is useful for identifying object references by their class names. We must provide the fully-qualified class name here. The three most important methods in this class are:įorName(), which loads a class of a given name, using the current class loader.

Class loaders in the JVM return objects of type Class. The special class Classis the universal type for the meta information that describes objects within the JVM.

Reflective codes expose internals as they break abstractions and therefore may change behavior with up-gradation of the platform.

#JAVA REFLECTION TUTORIAL FOR BEGINNERS CODE#

Reflective operations have slower performance compared to their non-reflective versions, and should be avoided in sections of code which are invoked frequently in performance-sensitive applications.

Debugging, Testing tools and IDEs (NetBeans, Eclipse etc.) can use the property of reflection to introspect members of the classes.

A Java application may make use of external, user-defined classes by creating instances of extensibility objects using their fully-qualified class names.

Every array with the same type and same dimension share the same instance of the class Class. It is also used to represent an instance of any Java array. int.class, double.class or boolean.class. We can get the corresponding Class instance by using class literals e.g. byte, short, int, long, float, double, char, and booleanare also represented by Class instances. The object of class Class is also used to represent classes, enums, interfaces and annotations in a Java application during runtime. The class has no public constructor and its instance is created by JVM itself when a class is loaded. newInstance() which is the backbone of Reflection API and allow us to create an instance of a class without using new() operator. which are used to find and load a class, we might have used them to load MySQL or Oracle drivers. It is very useful in the sense that it provides several utility methods such as getClass(), forName() etc. The is one of the most important class in Java programming.