Java Servlet :: Implementing JPA Hibernate Simple Application Using One To Many Relationship

I am implementing JPA hibernate simple application using one to many relationship.

Relation ship is Comapny (1)----------- Department(*)

Company.java is as follow :

package com.web.pojo;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;

[Code] .....     

What I am doing is , I am adding new department to existing company. After execution above code

Table created are :

1. Company table with id and name
2. Department table with deptId , deptName , compId.

so at the time adding department , it does not threw any exception but updates records in department as

1(Id),Development(DeptName),null(compId) .

I am not getting why it is not updating compId column.