Call private method of a class in java

Hi All,

We can execute/call/invoke private method of a Class with the help of Reflection and Mockit.
I give an example in which i have one class Student and that class having one private method showStudentDetails.
I have one another class StudentHack in which i execute that private method in two different methods.

Let us have a Student class
package com.om.demo;

public class Student {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
   
    private void showStudentDetails(){
        System.out.println("Student Name : "+name);
    }
}

Let us have another class StudentHack which Hack Student class

package com.om.demo;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import mockit.Deencapsulation;

public class StudentHack {

    // Object of Student class
    private Student student = null;
    // Name of the private method
    private String methodName = "showStudentDetails";

    {
        student = new Student();
        student.setName("Ram");
    }

    public static void main(String[] args) throws IllegalArgumentException,
            IllegalAccessException, InvocationTargetException,
            NoSuchMethodException, SecurityException {

        StudentHack studentHack = new StudentHack();
        studentHack.callPrivateMethodWithReflection();
        studentHack.callPrivateMethodWithMockit();
    }

    public void callPrivateMethodWithReflection()
            throws IllegalArgumentException, IllegalAccessException,
            InvocationTargetException, NoSuchMethodException, SecurityException {
        // Name of the class
        Class c = Student.class;
        // Create method instance
        Method method = c.getDeclaredMethod(methodName);
        // Allow to access private method
        method.setAccessible(true);
        // call private method
        method.invoke(student, new Object[] {});
    }

    public void callPrivateMethodWithMockit() {
        Deencapsulation.invoke(student, "showStudentDetails");
    }
}


As shown above we can execute private method of a class with the help of Reflection and Mockit

Call private method with Reflection
    Step 1.    Create instance of java.lang.reflect.Method i.e. Method method = c.getDeclaredMethod(methodName);
            where methodName is an argument, which we want to call
    Step 2.    Allow to access private method i.e. method.setAccessible(true);
    Step 3.    Invoke private method i.e. method.invoke(student, new Object[] {});
            Here new Object[] {} is the array of objects which represents argument of method.
            If method contains argument then we need to pass arguments here.

Call private method with Mockit
    Step 1. Deencapsulation.invoke(student, "showStudentDetails");
            If method contains argument then we pass array of Object as 3rd argument.
            i.e. Deencapsulation.invoke(student, "showStudentDetails", new Object[] {});