Accessing Private Methods using Java Reflection

Accessing Private Methods

Call Class.getDeclaredMethod(String name, Class[] paramTypes) or Class.getDeclaredMethods() method to obtain the private/public methods.

The methods Class.getMethod(String name, Class[] parameterTypes) and Class.getMethods() methods only return public methods.

package reflection;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

class PrivateObject  {

      private String string;

      public PrivateObject (String string) {

            this.string= string;

      }

      private String getPrivateMethod() {

            return string;

      }

}

public class TestReflectionMethod {

      public static void main(String[] args) {

          PrivateObject pvtObj = new PrivateObject("Private method");

          try {

              Method privateMethod =
                  PrivateObject.class.getDeclaredMethod
                  ("getPrivateMethod",null);

              /** SecurityException - if the request is denied. */

              privateMethod.setAccessible(true);

              String returnValue =

                           (String) privateMethod.invoke(pvtObj, null);

              System.out.println("using reflection="+returnValue+" accessed!!");

         } catch (IllegalAccessException e) {

         } catch (InvocationTargetException e) {

         } catch (NoSuchMethodException e) {

         }

     }

}

Output: using reflection = Private method accessed!!