Java：如何将用户输入与文本文件中的列进行比较？

Question

I'm pretty new to Java, so after several days of trying to figure out how to compare user input to a column in a text file, I am in desperate need of help. I want to be sure that an employee who punches-in has not punched-in once before without punching-out after that. In addition, I would like to be able to ensure that a user cannot punch-out of the system unless they have previously punched-in. I know that I have to split the lines in the text file in order to make them accessible separately, but I don't know how to compare them to user input. Any help is greatly appreciated! My code is as follows:

    import java.text.*;
    import java.util.*;
    import java.io.*;
    import java.nio.file.*;  

public class TimeClockApp
    {
    // declare class variables
    private static EmployeeDAO employeeDAO = null;
    private static TimeClockDAO timeClockDAO = null;
    private static Scanner sc = null;
    // format date and time / //HH converts hour in 24 hours format (0-23), day calculation
    private static DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

public static void main(String[] args) throws Exception
{
    // set the class variables
    employeeDAO = DAOFactory.getEmployeeDAO();
    timeClockDAO = DAOFactory.getTimeClockDAO();
    sc = new Scanner(System.in);
    int employeeID = 0;

    List<Employee> employees = employeeDAO.readEmployees();
    List<TimeClock> timePunches = timeClockDAO.readTimePunches();
    if(timePunches == null)
    {
        timePunches = new ArrayList<TimeClock>();
    }

    // display a welcome message
    System.out.println("Welcome to the Punch-In/Punch-Out Screen\n");

    // print option menu
    System.out.print("Please choose an option below:" + "\n"
           + "I. Punch In" + "\n"
           + "O. Punch Out" + "\n");

    String choice = "";
    // get input from user
    Scanner sc = new Scanner(System.in);

    while(choice != null)
    {
        // get input from user "i" or "o"
        while (!choice.equalsIgnoreCase("i") && !choice.equalsIgnoreCase("o"))
        {
            // it will not continue if user does not enter a valid choice
            choice = Validator.getScreenChoice(sc, "Choice: ");
            if(!choice.equalsIgnoreCase("i") && !choice.equalsIgnoreCase("o"))
            {
                System.out.println("Invalid choice.  Please try again.");
            }
        }
        System.out.println(); // print a blank line

        if(!choice.isEmpty())
        {
            // create employee object
            Employee employee = null;

            System.out.println("PUNCH CLOCK");
            System.out.println("-----------");

            // read employee ID and compare to employee.txt
            while(employee == null)
            {
                employeeID = Validator.getEmployeeID(sc,
                        "Enter Employee ID:    ");

                for(Employee e : employees)
                {
                    if(e.getEmployeeID() == employeeID)
                    {
                        employee = e;
                        break;
                    }
                }
            }
            // if employee ID is valid, have they punched in already?
            // if not, try again.

            // read timeclock.txt
           timeClockDAO.readTimePunches();

            if(employeeID == employee.getEmployeeID() && choice.equalsIgnoreCase("o")) // <-- This is where I'm having trouble
            {

               if(timePunches.contains("i"))
                {
                    if(timePunches.contains(employeeID))
                    {
                        System.out.println("Employee " + employeeID + " has already punched in. Please try again.");
                    }
                }

                // has employee punched in?  If yes, continue. <-- Beginning here, NetBeans ignores this whole deal
                for(TimeClock t : timePunches)
                {
                    if(t.getPunchInOrOut() && choice.equalsIgnoreCase("i"))
                    {
                        timePunches = t;
                        break;
                    }
                }
               // if employee has not punched in, try again
               if(timePunches.contains("i"))
                {
                    if(timePunches.contains(employeeID))
                    {
                        System.out.println("Employee " + employeeID + " has not punched in yet. Please try again.");
                    }
                }
            } // <-- NetBeans stops ignoring and continues from here

            TimeClock newTimePunch = new TimeClock(employeeID, new Date(), choice);

            // if employee ID is valid,
            // addition of date and time to arraylist/text file
            timePunches.add(newTimePunch);

            //write to the file
            timeClockDAO.writeTimePunch(newTimePunch);

            // conditional statement for in/out + formatting
            System.out.println("Punch-" + (choice.equalsIgnoreCase("i") ? "In" : "Out") + " Successful!" + "\n"
                             + "Date & Time:   " + dateFormat.format(new Date()) + "\n"
                             + "Employee Name: " + employee.getFirstName() + " " + employee.getLastName() + "\n"
                             + "Employee ID:   " + employee.getEmployeeID() + "\n");

            System.out.println(); // print a blank line
            break;
        }
        else
        {
            System.out.println("Invalid entry. Please try again.");
        }
    }

    // press enter to continue to the main screen
    System.out.printf("Press enter to return to the main screen. ");
    sc.nextLine();
    System.out.println("Okay, returning to Main Screen.  Goodbye!");
    System.out.println(); // print a blank line

    MainScreenApp.main(args);
}

}

Can I use the timeClockDAO.readTimePunches() portion of my code to read and compare columns in the text file to the user's input since the columns are already split there? The timeClockDAO.readTimePunches() method from the List<TimeClock> timePunches() list is as follows:

        @Override
public List<TimeClock> readTimePunches()
{
    if(timePunches != null)
        return timePunches;

    timePunches = new ArrayList<TimeClock>();
    DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

    if(Files.exists(Paths.get(timeClockPath))) // prevent the FileNotFoundException
    {
        try(BufferedReader in = new BufferedReader(
                                new FileReader(
                                new File(timeClockPath))))
        {
            // read all employees in the file into the array list
            String line = in.readLine();
            while(line != null)
            {
                // split text file into columns
                String[] columns = line.split(EmployeeTextFile.FIELD_SEP);
                /*if(columns.length != 3)
                {
                    System.err.println("Could not read text file for Time Punches.");
                    return null;
                }*/
                // employee ID column
                int employeeID = Integer.parseInt(columns[0]);
                // time stamp column
                Date timeStamp;
                try
                {
                    timeStamp = dateFormat.parse(columns[1]);
                }
                catch (ParseException e)
                {
                    System.err.println("Could not parse time stamp: " + columns[1]);
                    timeStamp = null;
                }
                // in or out column
                String punchInOrOut = columns[2];
                timePunches.add(new TimeClock(employeeID, timeStamp, punchInOrOut));

                line = in.readLine();
            }
        }
        catch(IOException e)
        {
            System.out.println(e);
            return null;
        }
    }
    return timePunches;
}

Thank you in advance!

Answer 1

The lines if(timePunches.contains("i")) and if(timePunches.contains(employeeID)) won't work since timePunches is an arrayList of TimeClock and unless you use a comparator or implement the Comparable interface, you cannot check if it contains a String value or an Employee value.

As I can assume in your code, you add timePunches to the end of the file so you only need to compare to the last item of your ArrayList to see if the current employee's state is punched in or punched out.

Instead of if(timePunches.contains("i")) and if(timePunches.contains(employeeID)) you should first fill your ArrayList only with your current Employee punches. Then, do something similar to:

if((timePunches.get(timePunches.size()).getPunchedInOrOut.equals("i") && choice.equals("o")) || (timePunches.get(timePunches.size()).getPunchedInOrOut.equals("o") && choice.equals("i")) ...