Reflection Field setValue for inner object

class User{
  Account account;
  String name; 
}

class Account {
  Integer amount;
}


**main :**
        User u = new User();
        Field field = u.getClass().getDeclaredField("account");
        field.setAccessible(true);
        Field amount = field.getType().getDeclaredField("amount");
        amount.set(field, new Integer(1000));

console :

 Exception in thread "main" java.lang.IllegalArgumentException: Can not set
 java.math.BigDecimal field com.company.Account.amount to java.lang.reflect.Field

How to set value into Account.