package examples;import java.io.Serializable;/** * Primary Key class for Account. */public class AccountPK     implements java.io.Serializable {    public String accountID;    public AccountPK(String id)     {	this.accountID = id;    }    public AccountPK()     {    }    public String toString()     {	return accountID;    }    public int hashCode()     {  	return accountID.hashCode();    }      public boolean equals(Object account)     {        if (!(account instanceof AccountPK))            return false;   	return ((AccountPK)account).accountID.equals(accountID);    }  }