Java Reflection

  Private methods and Fields Access with Java Reflection

Java Reflection, guess you heard it.But I will give a little bit of introduction and show some code sample to get familiar with this.
OK so the first thing first.
What is Java Reflection ?
Java Reflection can be used to dynamically find java classes , locating and execute methods, access fields at run time.

You can find More on : http://docs.oracle.com/javase/tutorial/reflect/index.html

Here is the sample project that I did.

First I create a class called dynamic test and add one private field and four methods including one private methods. Here is the code and its straight forward.

 package rd.test;  
 public class DynamicTest {  
   private int count;  
   public void printStar() {  
     System.out.println("*");  
   }  
   public void printStarWithInt(int i) {  
     System.out.println("* Integer : " + i);  
   }  
   public void printStarWithString(String param) {  
     System.out.println("* String : " + param);  
   }  
   public void printStarWithStrings(String param1, String param2) {  
     System.out.println("* String : " + param1 + " , and " + param2);  
   }  
   private void printStarInPrivate() {  
     System.out.println("* Private : *");  
   }  
 }  

and here is the class with main method.

 package rd;  
 import rd.test.DynamicTest;  
 import java.lang.reflect.Field;  
 import java.lang.reflect.InvocationTargetException;  
 import java.lang.reflect.Method;  
 public class Main {  
   public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException,  
       InstantiationException, NoSuchMethodException, InvocationTargetException, NoSuchFieldException {  
     Class cls = Class.forName("rd.test.DynamicTest");  
     Object obj = cls.newInstance();  
     /**  
      * calling printstart method without passing any parameters  
      * */  
     Method method = cls.getDeclaredMethod("printStar", null);  
     method.invoke(obj, null);  
     /**  
      * calling printStarWithInt method with int parameter  
      */  
     Class[] intParam = new Class[1];  
     intParam[0] = Integer.TYPE;  
     method = cls.getDeclaredMethod("printStarWithInt", intParam);  
     method.invoke(obj, 100);  
     /**  
      * calling printStarWithStrings methos with two string parameters  
      */  
     Class[] stringParams = new Class[2];  
     stringParams[0]=String.class;  
     stringParams[1]=String.class;  
     method = cls.getDeclaredMethod("printStarWithStrings", stringParams);  
     method.invoke(obj, "hi","rajith");  
     /**  
      * calling private method in DynamicTest class  
      */  
     method = cls.getDeclaredMethod("printStarInPrivate", null);  
     method.setAccessible(true);  
     method.invoke(obj, null);  
     /**  
      * setting and getting private fileds  
      */  
     DynamicTest dynamicTest = new DynamicTest();  
     Field field = cls.getDeclaredField("count");  
     field.setAccessible(true);  
     field.setInt(dynamicTest,10);  
     System.out.println(field.get(dynamicTest));  
   }  
 }