How to call a private method from outside a java class

Question

I have a Dummy class that has a private method called sayHello. I want to call sayHello from outside Dummy. I think it should be possible with reflection but I get an IllegalAccessException. Any ideas???

Answer 1

use setAccessible(true) on your Method object before using its invoke method.

import java.lang.reflect.*; class Dummy{     private void foo(){         System.out.println("hello foo()");     } }  class Test{     public static void main(String[] args) throws Exception {         Dummy d = new Dummy();         Method m = Dummy.class.getDeclaredMethod("foo");         //m.invoke(d);// throws java.lang.IllegalAccessException         m.setAccessible(true);// Abracadabra          m.invoke(d);// now its OK     } } 

Answer 2

First you gotta get the class, which is pretty straight forward, then get the method by name using getDeclaredMethod then you need to set the method as accessible by setAccessible method on the Method object.

    Class<?> clazz = Class.forName("test.Dummy");      Method m = clazz.getDeclaredMethod("sayHello");      m.setAccessible(true);      m.invoke(new Dummy());