How can hibernate access a private field?

Question

How can hibernate can access a private field/method of a java class , for example to set the @Id ?

Thanks

Answer 1

Like Crippledsmurf says, it uses reflection. See Reflection: Breaking all the Rules and Hibernate: Preserving an Object's Contract.

Answer 2

Try

import java.lang.reflect.Field;

class Test {
   private final int value;
   Test(int value) { this.value = value; }
   public String toString() { return "" + value; }
}

public class Main {
   public static void main(String... args) throws NoSuchFieldException, IllegalAccessException {
       Test test = new Test(12345);
       System.out.println("test= "+test);

       Field value = Test.class.getDeclaredField("value");
       value.setAccessible(true);
       System.out.println("test.value= "+value.get(test));
       value.set(test, 99999);
       System.out.println("test= "+test);
       System.out.println("test.value= "+value.get(test));
   }
}

prints

test= 12345
test.value= 12345
test= 99999
test.value= 99999

Answer 3

At a guess I would say that this is done by reflecting on the target type and setting the fields directly using reflection

I am not a java programmer but I believe java has reflection support similar to that of .NET which I do use