Package com.ntu.fdae.group1.bto.utils

Class FileUtil

java.lang.Object

com.ntu.fdae.group1.bto.utils.FileUtil

public final class FileUtil
extends Object

Utility class providing common file operations, CSV handling, and data parsing capabilities for the BTO Management System. This class offers static methods for:

• Reading from and writing to CSV files
• Parsing dates and enum values from strings
• Handling string operations common in file processing
• Safely parsing numeric types with default values

The class uses UTF-8 encoding for all file operations and ISO-8601 format for date handling. It is designed to be used throughout the application for consistent file and data manipulation.

Method Summary

Modifier and Type	Method	Description
static String	formatLocalDate(LocalDate date)	Formats a LocalDate into a string using the predefined ISO date format.
static String	joinList(List<String> list, String delimiter)	Joins a list of strings with a specified delimiter.
static Double	parseDoubleOrDefault(String value, Double defaultValue)	Safely parses a Double from a string with a fallback default value.
static <E extends Enum<E>> E	parseEnum(Class<E> enumClass, String value)	Safely parses an enum value from a string (case-insensitive).
static <E extends Enum<E>> E	parseEnum(Class<E> enumClass, String value, E defaultValue)	Safely parses an enum value from a string (case-insensitive) with a default value.
static Integer	parseIntOrDefault(String value, Integer defaultValue)	Safely parses an Integer from a string with a fallback default value.
static LocalDate	parseLocalDate(String dateString)	Safely parses a LocalDate from a string using the predefined ISO date format.
static List<String[]>	readCsvLines(String filePath)	Reads all lines from a CSV file, skipping the header.
static List<String>	splitString(String str, String delimiter)	Splits a delimited string into a List of strings.
static void	writeCsvLines(String filePath, List<String[]> data, String[] header)	Writes data to a CSV file, overwriting existing content.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

readCsvLines

public static List<String[]> readCsvLines(String filePath)
                                   throws IOException

Reads all lines from a CSV file, skipping the header. This method reads a CSV file, processes each line by:

• Skipping the header line
• Splitting each line by the CSV delimiter
• Removing double quotes from each field
• Ignoring empty lines

All file operations use UTF-8 encoding.

Parameters:

filePath - Path to the CSV file

Returns:

List of String arrays, where each array represents a row's columns

Throws:

IOException - If an I/O error occurs reading from the file

writeCsvLines

public static void writeCsvLines(String filePath,
 List<String[]> data,
 String[] header)
                          throws IOException

Writes data to a CSV file, overwriting existing content. This method handles the complete process of writing data to a CSV file:

• Creates parent directories if they don't exist
• Writes the header row first
• Writes each data row, joining column values with the CSV delimiter
• Overwrites the file if it already exists

All file operations use UTF-8 encoding.

Parameters:

filePath - Path to the CSV file to write to

data - List of String arrays representing rows (excluding header)

header - Array of strings for the header row

Throws:

IOException - If an I/O error occurs writing to the file

parseLocalDate

public static LocalDate parseLocalDate(String dateString)

Safely parses a LocalDate from a string using the predefined ISO date format. This method handles all potential parsing issues:

• Returns null for null or empty input strings
• Trims the input string before parsing
• Logs a warning if the date cannot be parsed

Parameters:

dateString - The string representation of a date to parse

Returns:

LocalDate object if successful, or null if parsing fails or input is invalid

formatLocalDate

public static String formatLocalDate(LocalDate date)

Formats a LocalDate into a string using the predefined ISO date format. This method handles:

• Returning an empty string for null dates
• Logging a warning if formatting fails
• Providing today's date as fallback if formatting fails

Parameters:

date - The LocalDate object to format

Returns:

Formatted date string, empty string for null dates, or current date if formatting fails

parseEnum

public static <E extends Enum<E>> E parseEnum(Class<E> enumClass,
 String value)

Safely parses an enum value from a string (case-insensitive). This method attempts to convert a string to an enum constant by:

• Converting the string to uppercase
• Trimming whitespace
• Returning null for null or empty input strings
• Logging a warning if the enum value cannot be parsed

Type Parameters:

E - The enum type

Parameters:

enumClass - The class of the enum

value - The string value to parse

Returns:

The enum constant if successful, or null if parsing fails or input is invalid

parseEnum

public static <E extends Enum<E>> E parseEnum(Class<E> enumClass,
 String value,
 E defaultValue)

Safely parses an enum value from a string (case-insensitive) with a default value. This method extends parseEnum(Class, String) by providing a default value when parsing fails. It:

• Returns the default value for null or empty input strings
• Logs a warning if the enum value cannot be parsed
• Returns the default value if parsing fails

Type Parameters:

E - The enum type

Parameters:

enumClass - The class of the enum

value - The string value to parse

defaultValue - The value to return if parsing fails or input is invalid

Returns:

The enum constant if successful, or the defaultValue if parsing fails

joinList

public static String joinList(List<String> list,
 String delimiter)

Joins a list of strings with a specified delimiter. This method:

• Filters out null values from the list
• Handles null or empty lists by returning an empty string
• Joins all remaining strings with the specified delimiter

Parameters:

list - The list of strings to join

delimiter - The delimiter to use between elements

Returns:

A single string with all elements joined, or empty string for null/empty lists

splitString

public static List<String> splitString(String str,
 String delimiter)

Splits a delimited string into a List of strings. This method:

• Handles null or empty input by returning an empty list
• Uses the specified delimiter as a regex for splitting
• Preserves trailing empty strings by using -1 as the limit parameter

Parameters:

str - The string to split

delimiter - The delimiter regex

Returns:

List of strings resulting from the split operation (potentially empty)

parseIntOrDefault

public static Integer parseIntOrDefault(String value,
 Integer defaultValue)

Safely parses an Integer from a string with a fallback default value. This method:

• Returns the default value for null or empty input strings
• Trims the input string before parsing
• Logs a warning if the number cannot be parsed
• Returns the default value if parsing fails

Parameters:

value - The string to parse

defaultValue - The default value to return if parsing fails

Returns:

The parsed integer or the default value

parseDoubleOrDefault

public static Double parseDoubleOrDefault(String value,
 Double defaultValue)

Safely parses a Double from a string with a fallback default value. This method:

• Returns the default value for null or empty input strings
• Trims the input string before parsing
• Logs a warning if the number cannot be parsed
• Returns the default value if parsing fails

Parameters:

value - The string to parse

defaultValue - The default value to return if parsing fails

Returns:

The parsed double or the default value