Access an object from another class in private method

Question

How do I access an object from another class in private method in Java ?

Simple example to call private method from another class.

File: A.java

public class A {  
  private void message(){System.out.println("hello java"); }  
}

File: MethodCall.java

import java.lang.reflect.Method;  
public class MethodCall{  
public static void main(String[] args)throws Exception{  

    Class c = Class.forName("A");  
    Object o= c.newInstance();  
    Method m =c.getDeclaredMethod("message", null);  
    m.setAccessible(true);  
    m.invoke(o, null);  
}  
}

Actually here is no major issues in the code you've showed. Why you're considering it as not working? — Sergey Prokofiev, Apr 19 '18 at 05:44
This is not a question. The solution for the question is given as example — janith1024, Apr 19 '18 at 07:05

score 2 · Accepted Answer · edited Apr 19 '18 at 06:19

2

Since private is used only in declared classes and it can not be called from other classes. If you want to use it, you should use it after modifying to protected or public.

edited Apr 19 '18 at 06:19

Aja

23
9

answered Apr 19 '18 at 05:41

jmingrove21

181
1
3
15

1

Sure you can, with the magic of [Reflection API](https://docs.oracle.com/javase/tutorial/reflect/index.html). – Sergey Prokofiev Apr 19 '18 at 05:45
@SergeyProkofiev Could the use of the Reflection API in the above code be a common solution to the problem of not using private? It 's a temporary solution. – jmingrove21 Apr 19 '18 at 05:50
what does it mean "temporary solution"? For sure author should double check why it's required to call private methods, but technically it is completely possible, so your statement is incorrect. – Sergey Prokofiev Apr 19 '18 at 05:52
@MinKyuJeong You can do this using "reflect". – Chamara Maduranga Apr 19 '18 at 06:23

score 0 · Answer 2 · answered Apr 19 '18 at 06:12

Normally Private methods can access only from within the same class. Can’t access the private methods from the outside class. However, there is a way to access the private methods from outside class.

import java.lang.reflect.Method;

public class PriavteMethodAccessTest{  

public static void main(String[] args)throws Exception{  

    A test = new A();
    Class<?> clazz = test.getClass();
    Method method = clazz.getDeclaredMethod("message");
    method.setAccessible(true);
    System.out.println(method.invoke(test));
}  
}

Access an object from another class in private method

2 Answers2