Question

I have a method where I want to factor out some code into its own method
This is what I have:

public class TD0301AssignmentForm extends Form {  
 public TD0301AssignmentForm(TD0301AssignmentDAO dao, STKUser authenticatedUser) {
    this.dao = dao;
    this.authenticatedUser = authenticatedUser;
 }

  public Object insert(HttpServletRequest request) {
    TD0301Assignment tdas = new TD0301Assignment();
    TD0301Assignment tdas_orig = null;
    Date dateNow = new Date();

    try {
        // Get the inuput from HTML form
        tdas.setCalc_num(FormUtil.getFieldValue(request, FIELD_CALC_NUM));
        processDate(request, tdas);
        tdas.setCalc_dept(FormUtil.getFieldValue(request, FIELD_CALC_DEPT));
        tdas.setYear_oi(Integer.toString(DateUtil.getIntYear(dateNow)));
        processCalcSafetyRequirements(request, tdas);
        ...etc...
        if (isSucces()) {
             // Instantiate a base work flow instance!
             WorkflowInstance wfi = new WorkflowInstance();
             WorkflowInstanceDAO wfiDAO = new WorkflowInstanceDAO();
             wfi.setWorkflow_class_id(tdas.getCalc_level());
             wfi.setStarted_by(authenticatedUser.getBadge());
             wfi.setStatus("0");
             wfi.setLast_date(dateNow);
             // Insert the WorkFlowInstance into the database, db sets returned sequence number into the wfi object.
             wfiDAO.insert(wfi, authenticatedUser);

             // Insert the TD0301Assignment into the db
             tdas.setWorkflow_instance_id(wfi.getWorkflow_instance_id());
          } 

I’d like to remove the WorkflowInstance code out into its own method (still in this Class) like this:

        if (isSucces()) {
            insertWorkFlowInstance(request, tdas);
            tdas.setWorkflow_instance_id(wfi.getWorkflow_instance_id());

but wfi is now marked by Eclipse as not available. Should I do something like this to fix the error so that I can still get the wfi.getWorkflow_instance_id() in the isSuccess block above? I know it removes the error, but I am trying to apply best practices.

public class TD0301AssignmentForm extends Form {
 private WorkflowInstance wfi = new WorkflowInstance();
 private WorkflowInstanceDAO wfiDAO = new WorkflowInstanceDAO();

Answer 1

Instance variables (“properties” or “fields”) are not necessarily the way to go if they’re not used throughout the entire class.

Variables should have the smallest scope possible–this makes code easier to reason about.

With some noise elided, and also guessing, it seems like the WorkflowInstance and WorkflowInstanceDao could be localized (names changed to match Java conventions):

public class TD0301AssignmentForm extends Form {  

    public Object insert(HttpServletRequest request) {
        TD0301Assignment tdas = new TD0301Assignment();

        try {
            tdas.setCalcNum(FormUtil.getFieldValue(request, FIELD_CALC_NUM));
            processDate(request, tdas);

            tdas.setCalcDept(FormUtil.getFieldValue(request, FIELD_CALC_DEPT));
            tdas.setYearOi(Integer.toString(DateUtil.getIntYear(dateNow)));
            processCalcSafetyRequirements(request, tdas);

            if (isSuccess()) {
                WorkflowInstance wf = buildWorkflow(tdas);
                tdas.setWorkflowInstanceId(wf.getId());
            }
        }
    }

    private buildWorkflow(TD0301Assignment tdas) {
        WorkflowInstance wfi = new WorkflowInstance();
        wfi.setWorkflowClassId(tdas.getCalcLevel());
        wfi.setStartedBy(authenticatedUser.getBadge());
        wfi.setStatus("0");
        wfi.setLastDate(new Date());

        WorkflowInstanceDao wfiDao = new WorkflowInstanceDao();
        wfiDao.insert(wfi, authenticatedUser);
    } 

}

Whether or not this is appropriate depends on how/if the WorkflowInstance is used in the rest of the method snippet you show. The DAO is almost certainly able to be localized.

As methods become smaller and easier to think about, they become more testable.

For example, buildWorkflow is almost easy to test, except that the DAO is instantiated “manually”. This means that testing the method will either (a) depend on having a working DAO layer, or (b) it must be mocked by a framework that can mock static utility methods (several can).