The DateTimeFormatter class is used to format and parse date-time objects in Java. It supports predefined standard formats, custom patterns, and locale-sensitive formatting, making it essential for applications involving date/time I/O.
Commonly Used Methods
Simple Program
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class FormatterExample {
public static void main(String[] args) {
LocalDateTime now = LocalDateTime.now();
DateTimeFormatter customFormatter = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");
String formatted = now.format(customFormatter);
System.out.println("Current Date-Time (formatted): " + formatted);
}
}LotusJavaPrince and Mahesh are working on a global banking portal that formats user transaction timestamps according to different countries’ locales and display styles. They want:
- ISO and custom pattern formatting.
- Locale-based formatting (e.g., French, US).
- Parsing user-inputted date strings back to
LocalDate.
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.FormatStyle;
import java.util.Locale;
public class FormatterCaseStudy {
public static void main(String[] args) {
System.out.println("Date-Time Formatter Portal - by LotusJavaPrince & Mahesh");
// 1. Custom Format
LocalDateTime now = LocalDateTime.now();
DateTimeFormatter customFmt = DateTimeFormatter.ofPattern("EEEE, MMM dd yyyy HH:mm:ss");
System.out.println("Custom Format: " + now.format(customFmt));
// 2. ISO Format
DateTimeFormatter isoFmt = DateTimeFormatter.ISO_LOCAL_DATE_TIME;
System.out.println("ISO Format: " + now.format(isoFmt));
// 3. Locale-based Format (US & France)
DateTimeFormatter usFormatter = DateTimeFormatter.ofLocalizedDate(FormatStyle.FULL).withLocale(Locale.US);
DateTimeFormatter frFormatter = DateTimeFormatter.ofLocalizedDate(FormatStyle.FULL).withLocale(Locale.FRANCE);
LocalDate date = LocalDate.of(2025, 5, 22);
System.out.println("US Locale: " + date.format(usFormatter));
System.out.println("FR Locale: " + date.format(frFormatter));
// 4. Parsing User Input
String inputDate = "22-05-2025";
DateTimeFormatter parseFormatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");
LocalDate parsedDate = LocalDate.parse(inputDate, parseFormatter);
System.out.println("Parsed Date: " + parsedDate);
}
}
/*
Date-Time Formatter Portal - by LotusJavaPrince & Mahesh
Custom Format: Thursday, May 22 2025 14:50:05
ISO Format: 2025-05-22T14:50:05.123
US Locale: Thursday, May 22, 2025
FR Locale: jeudi 22 mai 2025
Parsed Date: 2025-05-22
*/The DateTimeFormatter class is a core utility in the java.time API for:
- Formatting
LocalDate,LocalTime, andLocalDateTimeobjects. - Supporting standard and custom patterns.
- Enabling locale-aware formatting.
- Parsing strings into date-time objects, which is critical for user input validation.