Java reflection - impact of setAccessible(true)

Question

I\'m using some annotations to dynamically set values of fields in classes. Since I want to do this regardless of whether it\'s public, protected, or private, I am a calling

Answer 1

With setAccessible() you change the behavior of the AccessibleObject, i.e. the Field instance, but not the actual field of the class. Here's the documentation (excerpt):

A value of true indicates that the reflected object should suppress checks for Java language access control when it is used

And a runnable example:

public class FieldAccessible {
    public static class MyClass {
        private String theField;
    }

    public static void main(String[] args) throws Exception {
        MyClass myClass = new MyClass();
        Field field1 = myClass.getClass().getDeclaredField("theField");
        field1.setAccessible(true);
        System.out.println(field1.get(myClass)); // no exception
        Field field2 = myClass.getClass().getDeclaredField("theField");
        System.out.println(field2.get(myClass)); // IllegalAccessException
    }

}