Java Reflection

     A feature which allows the program to analyse the program at run time. You can modify the structure and behaviour of the program dynamically.

Features:

Creating objects:

A new object can be created at runtime. The object is instantiated using the constructor.

Accessing Class information:

It uses java.lang package to get the class information. It also gives the details about member variables, methods, constructors and modifiers.

Manipulating Fields:

 A class ‘Field’ is used to get and set the field values. Even you can modify the private value.

Dynamic method invocation:

‘Method’ class is used to invoke the methods on objects. This handles the methods without the name also.

Inspect annotations:

              It analyses the classes, methods, fields and other members. This is used to build the frameworks and libraries.

Create the java program to implement the java reflection is given below…..

Program implementation:

• ·       Include the built in packages.
• ·       Create a class with main() function.
• ·       Using a try catch block, include the coding.
• ·       Get the class name and assign to the class object.
• ·       Using method object,assign the declaredmethods.
• ·       Finally,method object is used to getName of the methods and display the names of the class.

Program:

import java.lang.reflect.Method;

public class ReflectionEg {

    public static void main(String[] args) {

        try {

            //This statement gives you the Class object for the class

            Class<?> clas1 = Class.forName("java.util.ArrayList");

             // Display the names of all methods in the class

            Method[] methods = clas1.getDeclaredMethods();

            for (Method method1 : methods) {

                System.out.println("Method name: " + method1.getName());

            }

         } catch (ClassNotFoundException e) {

            e.printStackTrace();

        }

    }

}

Output:

C:\raji\blog>javac ReflectionEg.java

C:\raji\blog>java ReflectionEg

Method name: remove

Method name: remove

Method name: size

Method name: get

Method name: equals

Method name: hashCode

Method name: clone

Method name: sort

Method name: indexOf

Method name: clear

Method name: lastIndexOf

Method name: isEmpty

Method name: replaceAll

Method name: add

……………………………………….

That’s all. The java program to illustrate java reflection is implemented successfully. Happy coding!!!