Using printf for Date and Time Formatting

The printf method provides a straigthforward way to format dates and times in Java. Format specifiers start with %t followed by a single letter that determines the output format.

Code Example

import java.util.Date;

public class DateFormatting {
    public static void main(String[] args) {
        Date currentDate = new Date();
        
        System.out.printf("Full date and time: %tc%n", currentDate);
        System.out.printf("ISO format: %tF%n", currentDate);
        System.out.printf("US format: %tD%n", currentDate);
        System.out.printf("12-hour with AM/PM: %tr%n", currentDate);
        System.out.printf("24-hour time: %tT%n", currentDate);
        System.out.printf("24-hour without seconds: %tR", currentDate);
    }
}

Output:

Full date and time: Mon Sep 10 10:43:36 CST 2012
ISO format: 2012-09-10
US format: 09/10/12
12-hour with AM/PM: 10:43:36 AM
24-hour time: 10:43:36
24-hour without seconds: 10:43

Using Parameter Indexes

When you need to refernece the same date object multiple times within a format string, you can use indexed parameters. The index must immediately follow % and end with $.

import java.util.Date;

public class DateFormatting {
    public static void main(String[] args) {
        Date currentDate = new Date();
        
        System.out.printf("%1$s %2$tB %2$td, %2$tY", "Expiration:", currentDate);
    }
}

Output:

Expiration: February 09, 2014

Using the < Flag

The < flag allows you to reuse the previously formatted argument. This simplifies format strings when the same date needs multiple conversions.

import java.util.Date;

public class DateFormatting {
    public static void main(String[] args) {
        Date currentDate = new Date();
        
        System.out.printf("%s %tB %<te, %<tY", "Expiration:", currentDate);
    }
}

Output:

Expiration: February 09, 2014

Individual Date Component Format Specifiers

These format specifiers extract specific components from a date object:

import java.util.Date;
import java.util.Locale;

public class DateComponentDemo {
    public static void main(String[] args) {
        Date sampleDate = new Date();
        
        // Abbreviated month name
        String result = String.format(Locale.US, "Month (short): %tb", sampleDate);
        System.out.println(result);
        System.out.printf("Month (short, local): %tb%n", sampleDate);
        
        // Full month name
        result = String.format(Locale.US, "Month (full): %tB", sampleDate);
        System.out.println(result);
        System.out.printf("Month (full, local): %tB%n", sampleDate);
        
        // Abbreviated weekday
        result = String.format(Locale.US, "Weekday (short): %ta", sampleDate);
        System.out.println(result);
        
        // Full weekday
        System.out.printf("Weekday (full, local): %tA%n", sampleDate);
        
        // Century (first two digits of year)
        System.out.printf("Century: %tC%n", sampleDate);
        
        // Last two digits of year
        System.out.printf("Year (last two): %ty%n", sampleDate);
        
        // Day of year
        System.out.printf("Day of year: %tj%n", sampleDate);
        
        // Month (two digits)
        System.out.printf("Month (two digits): %tm%n", sampleDate);
        
        // Day of month (two digits, zero-padded)
        System.out.printf("Day (zero-padded): %td%n", sampleDate);
        
        // Day of month (no padding)
        System.out.printf("Day (no padding): %te", sampleDate);
    }
}

Output:

Month (short): May
Month (short, local): 五月
Month (full): May
Month (full, local): 五月
Weekday (short): Thu
Weekday (full, local): 星期四
Century: 20
Year (last two): 17
Day of year: 124
Month (two digits): 05
Day (zero-padded): 04
Day (no padding): 4