I'm currently investing a lot of time in cleaning up my code.
I have a lot of If statements that handles my signup form in frontend.
I have a feeling that after reading the book "Clean code". That this is just ugly, however I didn't seem to find any "amazing/incredible" cleanup format for my code below.
lets say I have 15 more if-statements then this will cause a lot of duplicates, so are there any major improvements possible?
User userByUsername = userRepo.findByUsername(user.getUsername());
User userByEmail = userRepo.findUserByEmail(user.getEmail());
if (userByUsername != null && userByEmail != null) {
throw new AccountException("Email and username already exist");
}
if (userByUsername != null) {
throw new AccountException("Username already exist");
}
if (userByEmail != null) {
throw new AccountException("Email already exist");
}
Another example with another method:
public void addConditions(ReservationDto reservationDto) {
long roomId = roomService.findRoomByRoomName(reservationDto.getRoomName()).getRoomId();
// Check for adding room: Roomcapacity for timeslote reached
// If maxCapacityAfternoon reached, then only add to afternoon possible
int roomCapacity = roomService.findRoomByRoomId(roomId).getCapacity();
boolean maxCapacityMorning = roomCapacity <= getNumberOfReservationsForRoomByDateVoormiddag(roomId, reservationDto.getDate());
boolean maxCapacityAfternoon = roomCapacity <= getNumberOfReservationsForRoomByDateNamiddag(roomId, reservationDto.getDate());
boolean isMorning = reservationDto.isMorning();
boolean isAfternoon = reservationDto.isAfternoon();
capacityConditions(reservationDto, maxCapacityMorning, maxCapacityAfternoon);
// Check: Reservation can only be made when it meets the following conditions
// - Same user
// - is active
// - Morning and date overlap
// - Afternoon and date overlap
Reservation mappedReservation = mapReservationDto(reservationDto);
int amountOfReservationsForDay = reservationRepo.existsReservationForDay(mappedReservation.getUsername(), mappedReservation.getDate());
if (isMorning && isAfternoon) {
if (amountOfReservationsForDay > 0) {
throw new ServiceException(RESERVATION_MSG + FOR_FULL_DAY + reservationDto.getDate());
}
if (reservationRepo.existsReservationForMorning(mappedReservation.getUsername(), mappedReservation.getDate()) > 0
|| reservationRepo.existsReservationForAfterNoon(mappedReservation.getUsername(), mappedReservation.getDate()) > 0
) {
throw new ServiceException(RESERVATION_MSG + "in de voor- of namiddag.");
}
}
if (isMorning && !isAfternoon) {
if (amountOfReservationsForDay > 0) {
throw new ServiceException(RESERVATION_MSG + FOR_FULL_DAY + reservationDto.getDate());
}
if (reservationRepo.existsReservationForMorning(mappedReservation.getUsername(), mappedReservation.getDate()) > 0) {
throw new ServiceException(RESERVATION_MSG + "in de voormiddag.");
}
}
if (!isMorning && isAfternoon) {
if (amountOfReservationsForDay > 0) {
throw new ServiceException(RESERVATION_MSG + FOR_FULL_DAY + reservationDto.getDate());
}
if (reservationRepo.existsReservationForAfterNoon(mappedReservation.getUsername(), mappedReservation.getDate()) > 0) {
throw new ServiceException(RESERVATION_MSG + "in de namiddag");
}
}
if (!isMorning && !isAfternoon) {
throw new ServiceException("Selecteer een tijdstip voor uw reservatie");
}
}
As you can see my project has a lot of conditions when I want to add a reservation. These are only the add conditions and don't take into account the room capacity check. Which is a long list of If's as well
You could create an enum for all the data validation exceptions that can be thrown
public enum DataValidationError {
USERNAME_EXISTS,
EMAIL_EXISTS,
...
}
public static class AccountException extends Exception {
private final List<DataValidationError> errors;
public AccountException(List<DataValidationError> errors) {
this.errors = errors;
}
public List<DataValidationError> getErrors() {
return errors;
}
}
Usage:
List<DataValidationError> errors = new ArrayList<>();
User userByUsername = userRepo.findByUsername(user.getUsername());
User userByEmail = userRepo.findUserByEmail(user.getEmail());
if (userByUsername != null) {
errors.add(DataValidationError.USERNAME_EXISTS);
}
if (userByEmail != null) {
errors.add(DataValidationError.EMAIL_EXISTS);
}
if (!errors.isEmpty()) {
throw new AccountException(errors);
}
This way you could add as many errors in the enum and keep adding them to a list and throw it only once at the end.
I am not sure if any really major improvement can be applied here. But for example since you are throwing the same type of exception you might play around your error message and throw exception only once. Like:
if(userByEmail != null || userByUsername != null){
String message = (userByEmail != null ? "Email" : "Username") + " already exist";
if(userByEmail != null && userByUsername != null){
message = "Email and username already exist";
}
throw new AccountException(message);
}
For make the code more extensible and close I would use a chain of validation for this kind of things. If you know about the SOLID principle, you have a problem of SRP and OCP. By implementing a chain of validation, you would have each node have one purpose and you could easily and more validation in the futur. After you just have to create a chain !
The thing is that validation is ONE thing, so I would too create lost of tiny function with good names, so the reader can "escape early" the reading if needed.
Here is the design patern that could help you: https://refactoring.guru/design-patterns/chain-of-responsibility
I think you repository should thow those exceptions too ! If you can't find a user throw an exception in your repository. You'll have less validation all over you code and it's easyer to read.
Related
my first time asking here so sorry if not asking properly
public class Person
{
private String name;
private Date born;
private Date died; //null indicates still alive.
public Person(String initialName, Date birthDate, Date deathDate)
{
if (consistent(birthDate, deathDate))
{
name = initialName;
born = new Date(birthDate);
if (deathDate == null)
{
died = null;
}
else
{
died = new Date(deathDate);
}
}
else
{
System.out.println("Inconsistent dates.Aborting.");
System.exit(0);
}
}
}
I have this code in my book. It is only part of the code, it is not a full code. I copied only the part that I was asking about. And my question is. Can't we just remove if (deathDate == null). If it is null, then died will be null anyway?
Keep reading. There is an else statement. What you propose is to replace this:
if (deathDate == null) died = null;
else died = new Date(deathDate);
with:
died = new Date(deathDate);
which won't work; that would boil down to new Date(null) which will throw NullPointerException.
NB: This is crazy code. When a precondition fails (inconsistent dates), you throw an exception. You don't print something to standard err and exit the entire VM. Replace those last two lines with throw new IllegalArgumentException("Death date cannot be before birth date. Death: " + death + " birth: " +birth);.
You may as well replace the code:
if (deathDate == null)
{
died = null;
}
else
{
died = new Date(deathDate);
}
into this:
died = null;
if (deathDate != null)
{
died = new Date(deathDate);
}
I have a TransferReader class which reads a file containing transfer data from bank account to another using the following form:
SenderAccountID,ReceiverAccountID,Amount,TransferDate
"473728292,474728298,1500.00,2019-10-17 12:34:12" (unmodified string)
Suppose that the file has been modified before being read so that one of the above mentioned paramaters are missing, and I want to check which of those are missing.
"474728298,1500.00,2019-10-17 12:34:12" (modified string)
I am using a BufferedReader to read each line, and then splitting each element into a String[] using String.split(",") as delimeter.
As already realized, because the Sender Account ID and Receiver Account ID are right next to one another within a record there is no real way of knowing which ID might be missing unless a delimiter remains in its' place indicating a Null value. There are however mechanisms available to determine that it is indeed one of the two that is missing, which one will need to be carried out through User scrutiny and even then, that may not be good enough. The other record column fields like Amount and Transfer Date can be easily validated or if missing can be implicated within a specific File Data Status Log.
Below is some code that will read a data file (named Data.csv) and log potential data line (record) errors into a List Interface object which is iterated through and displayed within the Console Window when the read is complete. There are also some small helper methods. Here is the code:
private void checkDataFile(String filePath) {
String ls = System.lineSeparator();
List<String> validationFailures = new ArrayList<>();
StringBuilder sb = new StringBuilder();
// 'Try With Resources' used here to auto-close reader.
try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
String line;
int lineCount = 0;
// Read the file line-by-line.
while ((line = reader.readLine()) != null) {
line = line.trim();
lineCount++;
if (lineCount == 1 || line.equals("")) {
continue;
}
sb.delete(0, sb.capacity()); // Clear the StringBuilder object
// Start the Status Log
sb.append("File Line Number: ").append(lineCount)
.append(" (\"").append(line).append("\")").append(ls);
// Split line into an Array based on a comma delimiter
// reguardless of the delimiter's spacing situation.
String[] lineParts = line.split("\\s{0,},\\s{0,}");
/* Validate each file line. Log any line that fails
any validation for any record column data into a
List Interface object named: validationFailures
*/
// Are there 4 Columns of data in each line...
if (lineParts.length < 4) {
sb.append("\t- Invalid Column Count!").append(ls);
// Which column is missing...
// *** You may need to add more conditions to suit your needs. ***
if (checkAccountIDs(lineParts[0]) && lineParts.length >= 2 && !checkAccountIDs(lineParts[1])) {
sb.append("\t- Either the 'Sender Account ID' or the "
+ "'ReceiverAccountID' is missing!").append(ls);
}
else if (lineParts.length >= 3 && !checkAmount(lineParts[2])) {
sb.append("\t- The 'Amount' value is missing!").append(ls);
}
else if (lineParts.length < 4) {
sb.append("\t- The 'Transfer Date' is missing!").append(ls);
}
}
else {
// Is SenderAccountID data valid...
if (!checkAccountIDs(lineParts[0])) {
sb.append("\t- Invalid Sender Account ID in column 1! (")
.append(lineParts[0].equals("") ? "Null" :
lineParts[0]).append(")");
if (lineParts[0].length() < 9) {
sb.append(" <-- Not Enough Or No Digits!").append(ls);
}
else if (lineParts[0].length() > 9) {
sb.append(" <-- Too Many Digits!").append(ls);
}
else {
sb.append(" <-- Not All Digits!").append(ls);
}
}
// Is ReceiverAccountID data valid...
if (!checkAccountIDs(lineParts[1])) {
sb.append("\t- Invalid Receiver Account ID in coloun 2! (")
.append(lineParts[1].equals("") ? "Null" :
lineParts[1]).append(")");
if (lineParts[1].length() < 9) {
sb.append(" <-- Not Enough Or No Digits!").append(ls);
}
else if (lineParts[1].length() > 9) {
sb.append(" <-- Too Many Digits!").append(ls);
}
else {
sb.append(" <-- Not All Digits!").append(ls);
}
}
// Is Amount data valid...
if (!checkAmount(lineParts[2])) {
sb.append("\t- Invalid Amount Value in column 3! (")
.append(lineParts[2].equals("") ? "Null" :
lineParts[2]).append(")").append(ls);
}
// Is TransferDate data valid...
if (!checkTransferDate(lineParts[3], "yyyy-MM-dd HH:mm:ss")) {
sb.append("\t- Invalid Transfer Date Timestamp in column 4! (")
.append(lineParts[3].equals("") ? "Null" :
lineParts[3]).append(")").append(ls);
}
}
if (!sb.toString().equals("")) {
validationFailures.add(sb.toString());
}
}
}
catch (FileNotFoundException ex) {
System.err.println(ex.getMessage());
}
catch (IOException ex) {
System.err.println(ex.getMessage());
}
// Display the Log...
String timeStamp = new SimpleDateFormat("yyyy/MM/dd - hh:mm:ssa").
format(new Timestamp(System.currentTimeMillis()));
String dispTitle = "File Data Status at " + timeStamp.toLowerCase()
+ " <:-:> (" + filePath + "):";
System.out.println(dispTitle + ls + String.join("",
Collections.nCopies(dispTitle.length(), "=")) + ls);
if (validationFailures.size() > 0) {
for (String str : validationFailures) {
if (str.split(ls).length > 1) {
System.out.println(str);
System.out.println(String.join("", Collections.nCopies(80, "-")) + ls);
}
}
}
else {
System.out.println("No Issues Detected!" + ls);
}
}
private boolean checkAccountIDs(String accountID) {
return (accountID.matches("\\d+") && accountID.length() == 9);
}
private boolean checkAmount(String amount) {
return amount.matches("-?\\d+(\\.\\d+)?");
}
private boolean checkTransferDate(String transferDate, String format) {
return isValidDateString(transferDate, format);
}
private boolean isValidDateString(String dateToValidate, String dateFromat) {
if (dateToValidate == null || dateToValidate.equals("")) {
return false;
}
SimpleDateFormat sdf = new SimpleDateFormat(dateFromat);
sdf.setLenient(false);
try {
// If not valid, it will throw a ParseException
Date date = sdf.parse(dateToValidate);
return true;
}
catch (ParseException e) {
return false;
}
}
I'm not exactly sure what your particular application process will ultimately entail but if other processes are accessing the file and making modifications to it then it may be wise utilize a locking mechanism to Lock the file during your particular process and Unlock the file when it is done. This however will most likely require you to utilize a different reading algorithm since locking a file must be done through a writable channel. Using the FileChannel and FileLock classes from the java.nio package could possibly assist you here. There would be examples of how to utilize these classes within the StackOverflow forum.
I tried to find a similar question, but I didn't succeed.
In a bean, I'm looping through a ViewEntryCollection several times, adding or deleting entries. Could someone tell me exactly when these objects should be recycled? I want to be able to reuse the whole collection so I don't want to destroy any objects I might still need.
My code:
public static int FTSearchAll(ViewEntryCollection vec, View vw, String cat, String query) throws NotesException {
...
for (ViewEntry ve = nav.getFirst(); ve != null; ) {
ViewEntry next = nav.getNext(ve);
Document doc = ve.getDocument();
if (doc == null)
continue;
try {
Vector v = session.evaluate(query, doc);
if (v != null && v.size() > 0 && (Double) v.elementAt(0) != 0) {
vec.addEntry(ve, false);
} else {
for (ViewEntry dce = vec.getFirstEntry(); dce != null;) {
ViewEntry dcnext = vec.getNextEntry(dce);
if (dce.getNoteID().equals(ve.getNoteID())) {
vec.deleteEntry(dce);
incinerate(dce);
break;
}
dce = dcnext;
}
}
} catch (NotesException ne) {
} finally {
incinerate(ve, doc);
}
ve= next;
}
As always: thanks!
The rule is quite simple: when a Java object pointing to a Notes C object is about to go onto the garbage heap, .recycle() must have been called.
So you need to do that for all entries inside the loop.
My little rule of thumb: the block (think { ... } ) that created a Notes Java object must call its .recycle() function at the end.
Saves you lot of headaches
I see this, but not completely sure whether I miss something or the code keeps its functionality... :S
for (ViewEntry ve = nav.getFirst(); ve != null; ) {
ViewEntry next = nav.getNext(ve);
Document doc = ve.getDocument();
if (doc == null) {
incinerate(ve); // << new
ve = next; // << new
continue;
}
try {
Vector v = session.evaluate(query, doc);
if (v != null && v.size() > 0 && (Double) v.elementAt(0) != 0) {
vec.addEntry(ve, false);
} else {
for (ViewEntry dce = vec.getFirstEntry(); dce != null;) {
ViewEntry dcnext = vec.getNextEntry(dce);
if (dce.getNoteID().equals(ve.getNoteID())) {
vec.deleteEntry(dce);
incinerate(dce, dcnext); // << new
break;
}
incinerate(dce); // << new
dce = dcnext;
}
}
} catch (NotesException ne) {
} finally {
incinerate(ve, doc);
}
ve = next;
}
Maybe it would be better to check another implementation.
Anyway, I recommend you to use the OpenNTF Domino API and get rid of recycle, and you will get also a proper iteration over entries:
http://www.openntf.org/main.nsf/project.xsp?r=project/OpenNTF%20Domino%20API
I have a java code in which there are multiple return statements in a single method. But for code cleaning purpose, I can have only one return statement per method. What can be done to overcome this.
Here is a method from my code:-
public ActionForward login(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception {
// Kill any old sessions
//request.getSession().invalidate();
DynaValidatorForm dynaform = (DynaValidatorForm)form;
// validate the form
ActionErrors errors = form.validate(mapping, request);
if(!errors.isEmpty()) {
this.saveErrors(request, errors);
return mapping.getInputForward();
}
// first check if token is set
if(!isTokenValid(request, true)) {
String errmsg="There was a problem with your login. Please close your browser then reopen it and try again. Make sure to click the Login button only ONCE.";
request.setAttribute("errormessage", errmsg);
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
// check the form for input errors
String errmsg = checkInput(form);
if (errmsg != null) {
request.setAttribute("errormessage", errmsg);
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
// no input errors detected
String resumekey = null;
// check for valid login
ObjectFactory objFactory = ObjectFactory.getInstance();
DataAccessor dataAccessor = objFactory.getDataAccessor();
request.setCharacterEncoding("UTF-8");
String testcode = dynaform.getString("testcode").trim();
String studentname = dynaform.getString("yourname").trim();
String password = dynaform.getString("password").trim();
// 4/3/07 - passwords going forward are ALL lower case
if (!CaslsUtils.isEmpty(password)) {
password = password.toLowerCase();
}
try{
resumekey = new String(studentname.getBytes("ISO-8859-1"),"UTF-8");
} catch (Exception e) {
log_.error("Error converting item content data to UTF-8 encoding. ",e);
}
String hashWord = CaslsUtils.encryptString(password);
// Make sure this is short enough to fit in the db
if (hashWord.length() > ConstantLibrary.MAX_PASSWORD_LENGTH) {
hashWord = hashWord.substring(0, ConstantLibrary.MAX_PASSWORD_LENGTH);
}
Login login = dataAccessor.getLogin(testcode, hashWord, false);
if (login == null || !login.getUsertype().equals(Login.USERTYPE_SUBJECT)) {
request.setAttribute("errormessage", "Incorrect test code or password.");
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
// Check if the login has expired
if (login.getLoginexpires() != null && login.getLoginexpires().before(new Date())) {
request.setAttribute("errormessage", "Your login has expired.");
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
// Check if the password has expired
if (login.getPasswordexpires() != null && login.getPasswordexpires().before(new Date())) {
request.setAttribute("errormessage", "Your login password has expired.");
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
HttpSession session = request.getSession();
session.setAttribute(ConstantLibrary.SESSION_LOGIN, login);
session.setAttribute(ConstantLibrary.SESSION_STUDENTNAME, studentname);
List<Testtaker> testtakers = null;
try {
//invalidate the old session if the incoming user is already logged in.
synchronized(this){
invalidateExistingSessionOfCurrentUser(request, studentname, testcode);
testtakers = dataAccessor.getTesttakersByResumeKey(studentname, login);// Adding this code to call getTesttakersByResumeKey instead of getTesttakers to improve the performance of the application during student login
}
} catch (Exception e) {
log.error("Exception when calling getTesttakers");
CaslsUtils.outputLoggingData(log_, request);
throw e;
}
session = request.getSession();
if(testtakers!=null)
{
if(testtakers.size() == 0) {
// new student -> start fresh
log_.debug("starting a fresh test");
// if this is a demo test, skip the consent pages and dump them directly to the select test page
if (login.getTestengine().equals(Itemmaster.TESTENGINE_DEMO)) {
return mapping.findForward("continue-panel");
}
}
// send them to fill out the profile
// check for custom profiles
String[] surveynames = new String[4];
List<Logingroup> logingroups = dataAccessor.getLoginGroupsByLogin(login.getLoginid());
for(Logingroup logingroup : logingroups) {
Groupmaster group = logingroup.getGroupmaster();
log_.debug(String.format("group: {groupid: %d, grouptype: %s, groupname: %s}", new Object[] {group.getGroupid(), group.getGrouptype(), group.getName()}));
Set<Groupsurvey> surveys = group.getGroupsurveys();
if(surveys.size() > 0) {
// grab the first (and only) one
Groupsurvey survey = surveys.toArray(new Groupsurvey[0])[0];
if(group.getGrouptype().equalsIgnoreCase(Groupmaster.GROUPTYPE_CLASS)) {
surveynames[0] = survey.getSurveyname();
} else if (group.getGrouptype().equalsIgnoreCase(Groupmaster.GROUPTYPE_SCHOOL)){
surveynames[1] = survey.getSurveyname();
} else if (group.getGrouptype().equalsIgnoreCase(Groupmaster.GROUPTYPE_DISTRICT)){
surveynames[2] = survey.getSurveyname();
} else if (group.getGrouptype().equalsIgnoreCase(Groupmaster.GROUPTYPE_STATE)){
surveynames[3] = survey.getSurveyname();
}
}
}
// match the most grandular survey
for(int i=0; i < surveynames.length; ++i) {
if(surveynames[i] != null) {
saveToken(request);
return mapping.findForward("student-profile-"+surveynames[i]);
}
}
// no custom profile, send them to the default
saveToken(request);
return mapping.findForward("student-profile");
}
// get the set of availible panels
Set<Panel> availiblePanels = dataAccessor.getAvailiblePanels(login, studentname);
if(availiblePanels.size() == 0) {
// no panels availible. send to all done!
log_.debug(String.format("No panels availible for Login:%s with resumekey:%s", login.toString(), studentname));
session.setAttribute("logoutpage", true);
resetToken(request);
return mapping.findForward("continue-alldone");
}
//Eventum #427 - Prevent test takers from retaking a finished test.
TestSubjectResult testSubjecResult=dataAccessor.getTestSubjectResult(login, resumekey);
if(testSubjecResult != null){
if(testSubjecResult.getRdscore() != null && testSubjecResult.getWrscore() != null && testSubjecResult.getLsscore() != null && testSubjecResult.getOlscore() != null){
if(testSubjecResult.getRdscore().getFinishtime() != null && testSubjecResult.getWrscore().getFinishtime() != null && testSubjecResult.getLsscore().getFinishtime() != null && testSubjecResult.getOlscore().getFinishtime() != null){
log_.debug(String.format("Already completed all the Skill Tests.", login.toString(), studentname));
session.setAttribute("logoutpage", true);
resetToken(request);
return mapping.findForward("continue-alldone");
}
}
}
// get a list of resumeable testtakers
List<Testtaker> resumeableTesttakers = new ArrayList<Testtaker>();
for(Testtaker testtaker : testtakers) {
if(testtaker.getPhase().equals(ConstantLibrary.PHASE_GOODBYE)) {
// testtaker is done with test. skip.
continue;
}
if(testtaker.getCurrentpanelid() == null) {
// testtaker is the profile testtaker
continue;
}
resumeableTesttakers.add(testtaker);
}
// sort them from least recent to latest
Collections.sort(resumeableTesttakers, new Comparator<Testtaker>() {
#Override
public int compare(Testtaker o1, Testtaker o2) {
// TODO Auto-generated method stub
//return 0;
return new CompareToBuilder()
.append(o1.getLasttouched(), o2.getLasttouched())
.toComparison();
}
});
if(resumeableTesttakers.size() == 0 && availiblePanels.size() > 0) {
// nobody is resumeable but there are panels left to take
// send them to the panel choice
// TODO: This is probably a misuse of Struts.
log_.info("No resumeable testtakers. Sending to panel select");
saveToken(request);
ActionForward myForward = (new ActionForward("/do/capstartpanel?capStartPanelAction=retest&lasttesttakerid="
+ testtakers.get(0).getTesttakerid(), true));
return myForward;// mapping.findForward(ConstantLibrary.FWD_CONTINUE + "-panel");
} else {
// grab the one most recently created and take their test
log_.info(String.format("Resuming with choice of %d testtakers", resumeableTesttakers.size()));
// we're forwarding to resume at this point, so we should do the some of the initialization
// that would have happened if we were still using getTesttaker() instead of getTesttakers() above.
session.setAttribute(ConstantLibrary.SESSION_LOGIN, login);
session.setAttribute(ConstantLibrary.SESSION_TESTTAKER, resumeableTesttakers.get(resumeableTesttakers.size()-1));
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_RESUME);
}
}
It's not a worth changing multiple returns to a single return statement per method. Actually, that will unnecessarily increase the burden of storing the result in a local variable and then making the return finally,
ActionForward result = null;
//scenario 1
result = ...
//scenario 2
result = ...
//scenario 3
result = ...
//finally
return result;
Hope this helps, but, it doesn't make much sense to me
As pointed out by others, having a single return statement does not necessarily make your code cleaner. However, in this case splitting up the method in smaller pieces probably makes the code more readable.
For example, this part:
// first check if token is set
if(!isTokenValid(request, true)) {
String errmsg="There was a problem with your login. Please close your browser then reopen it and try again. Make sure to click the Login button only ONCE.";
request.setAttribute("errormessage", errmsg);
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
// check the form for input errors
String errmsg = checkInput(form);
if (errmsg != null) {
request.setAttribute("errormessage", errmsg);
saveToken(request);
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
could be replaced by introducing two methods and using those to write:
If(tokenNotSet() || formHasErrors()){
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
}
By doing this on multiple places the structure of the algorithm becomes more clear, possibly giving you more insight in how this code could be refactored to adhere to your coding guidelines.
I would set a an action forward variable at the start of the method.
ActionForward actionForwardToReturn = null;
Then replace each of these two lines
return mapping.getInputForward();
return mapping.findForward(ConstantLibrary.FWD_CONTINUE);
with these two lines :
actionForwardToReturn = mapping.getInputForward()
actionForwardToReturn = mapping.findForward(ConstantLibrary.FWD_CONTINUE);
finally return the variable.
return actionForwardToReturn;
This shouldn't be too difficult :)
On a side note... (actually the orginal answer to the question) :
Multiple return statements can make it hard to debug code.
I personally would have just one action object that you return at the end of the method. The benefit of this, is that i can put a break point right on the return statement and look at exactly what that object is.
Any logging or other cross cutting concern I would want to add later, would only have to be done at one point. Otherwise I would have to add a log statement to every line where you are returning.
The complexity added to a method in an attempt to remove multiple return statements is many a times not worth it, especially in a method such as yours.There's nothing wrong with using them in this case.
Like user3580294 there's nothing wrong with multiple return statements. However you could combine the last two if statements since they are essentially returning the same thing.
Use #Octopus 's method if you absolutely have to have one return statement
private void btnOKActionPerformed(java.awt.event.ActionEvent evt)
{
try
{
if(txtStaffID.getText(0, 2).equals("AD"))
{
for(Admin admin:admincontrolpanel.adminList)
{
if(txtUsername.getText().equals("") || txtPassword.getText().equals("") || txtName.getText().equals("") || txtEmail.getText().equals("") || txtContactNumber.getText().equals("") || txtICNumber.getText().equals(""))
{
JOptionPane.showMessageDialog(null, "Please fill in the blank", "ERROR", JOptionPane.ERROR_MESSAGE);
}
else if(txtUsername.getText() != null && txtPassword.getText() != null && txtName.getText() != null && txtEmail.getText() != null && txtContactNumber.getText() != null && txtICNumber.getText() != null)
{
admin.setId(txtStaffID.getText());
admin.setUsername(txtUsername.getText());
admin.setPassword(txtPassword.getText());
admin.setName(txtName.getText());
admin.setEmail(txtEmail.getText());
admin.setContactNumber(txtContactNumber.getText());
admin.setIcNumber(txtICNumber.getText());
Admin newAdmin = new Admin(admin.getId(),admin.getUsername(),admin.getPassword(),admin.getName(),admin.getEmail(),admin.getContactNumber(),admin.getIcNumber());
admincontrolpanel.adminList.remove(admin);
admincontrolpanel.adminList.add(newAdmin);
}
}
JOptionPane.showMessageDialog(null, "Successfully Added!", "Add Staff", JOptionPane.PLAIN_MESSAGE);
dispose();
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
Inside the text file got these data...
AD001|jeff|jeff|jeff|jeff#gmail.com|123456|123456
AD002|admin|admin|admin|admin#gmail.com|123456|123456
When I press OK button to edi...it shows me this ConcurrentModificationException error....Anyone can help me to take a look of it??
Admin is the class...adminList is the arraylist...
try
{
PrintWriter pw = new PrintWriter("Admin.txt");
for(Admin admin:admincontrolpanel.adminList)
{
pw.println(admin.getId() + "|" + admin.getUsername() + "|" + admin.getPassword() + "|" + admin.getName() + "|" + admin.getEmail() + "|" + admin.getContactNumber() + "|" + admin.getIcNumber());
}
pw.close();
}
catch(Exception e)
{
e.printStackTrace();
}
This is the code i want to write into the text file from arraylist....
then it gave me this kind of data inside the arraylist...can edit it..but deleted the 1st data and add a new data into it
AD002|admin|admin|admin|admin#gmail.com|123456|123456
AD002|admin|admin|admin|admin#gmail.com|999|123456
A quick search through SO would have quickly shown you possible solutions..you can use a standard for loop and loop until the previous list's size, instead of using an implicit Iterator the way you are:
ArrayList<Admin> = admincontrolpanel.adminList;
int adminListSize = adminList.size();
for(int i=0;i<adminListSize;i++) {
Admin admin = adminList.get(i);
Or you can use a ListIterator to loop through the list using an Iterator and modify it.
Also, admincontrolpanel is not a good variable name. Use camelCase.
for(Admin admin:admincontrolpanel.adminList)
Through this loop you are iterating adminList(ArrayList)
Admin newAdmin = new Admin(admin.getId(),admin.getUsername(),admin.getPassword(),admin.getName(),admin.getEmail(),
admin.getContactNumber(),admin.getIcNumber());
admincontrolpanel.adminList.remove(admin);
admincontrolpanel.adminList.add(newAdmin);
above in last two line you are removing and adding ArrayList item which is not allowed here because you already iterating ArrayList. you can not do iterating and modifying ArrayList at the same time here. thats why you are facing Concurrent..exception.
This problem may occur due to thread inside another thread. For example if your are executing some code in your first thread and along this you have another thread inside this thread. then this problem occur.