public class Customer
{
private String id;

public Customer(String id)
{
setId(id);
}

public void setId(String id)
{
this.id = id;
}

public String getId()
{
return id;
}
}

import java.util.List;

//represents a Customer table within a datasource
public interface CustomerDAO
{
List<Customer> getCustomers();
Customer getCustomerById(String id);

boolean updateCustomer(Customer c);
boolean insertCustomer(Customer c);
boolean deleteCustomer(Customer c);
}

import java.util.List;

//communicates with datasource to obtain/modify/delete Customer objects
//stub because I am lazy
public class CustomerDAOImpl implements CustomerDAO
{
public CustomerDAOImpl() {}

public List<Customer> getCustomers() {}

public Customer getCustomerById(String id) {}

public boolean updateCustomer(Customer c) {}

public boolean insertCustomer(Customer c) {}

public boolean deleteCustomer(Customer c) {}

}

import java.util.List;

//represents the client
public class Store {

private CustomerDAO customerDAO;

public Store(CustomerDAO customerDAO)
{
this.customerDAO = customerDAO;
}

public Customer getCustomerByID(String id)
{
return customerDAO.getCustomerById(id);
}
}

package courseCatalog;

public class DbInteraction {
private int studentID;
private Connection conn;
Statement stmt = null;
PreparedStatement pStmt = null;
String query = ("");


public DbInteraction(int studentID, Connection conn)
{
this.studentID = studentID;
this.conn = conn;
}

public boolean validID() throws SQLException
{
this.setQuery("Select s.ID FROM STUDENT s WHERE s.ID = ?");
this.pStmt = conn.prepareStatement(this.query);
this.pStmt.setInt(1, this.studentID);

ResultSet rs = this.pStmt.executeQuery();
return rs.isBeforeFirst();
}



public Statement getStmt() {
return stmt;
}


public void setStmt(Statement stmt) {
this.stmt = stmt;
}


public String getQuery() {
return query;
}


public void setQuery(String query) {
this.query = query;
}


public int getStudentID() {
return studentID;
}


public void setStudentID(int studentID) {
this.studentID = studentID;
}


}

public MockCustomerDAO implements CustomerDAO
{
private List<Customer> customers = new List<Customer> { new Customer("Minko"), new Customer("Midnight") };

public List<Customer> getCustomers() { return customers; }

private Customer get(String id)
{
for(Customer c : customers)
if(c.getId().equals(id)) return c;
return null;
}
public Customer getCustomerById(String id)
{
return get(id);
}

//this method makes no sense because I only have 1 property on the Customer class
public boolean updateCustomer(Customer c)
{
Customer cust = get(c.getId());

if(cust == null) return false;

//set all of cust properties
cust.setId(c.getId());

return true;

}

public boolean insertCustomer(Customer c)
{
customers.add(c);
return true;
}

public boolean deleteCustomer(Customer c)
{
c = get(c.getId());
return customers.remove(c);
}

}