Here is a sample code by which you can hack and call the private constructor of a class using reflection.
public class HackMeIfYouCan {
private HackMeIfYouCan(){
System.out.println(“I m hacked”);
}
}
private HackMeIfYouCan(){
System.out.println(“I m hacked”);
}
}
public class Test {
public static void main(String[] args) throws Exception {
Constructor c[] = HackMeIfYouCan.class.getDeclaredConstructors();
c[0].setAccessible(true);
c[0].newInstance(null);
}
}
Here is the output of this program
I m hacked
So if you want your java class to be protected make sure you dont give ReflectPermission to your class.