Lära Formatting Dates with DateTimeFormatter | Parsing Dates and Formatting Tables

Date formatting is a common requirement in any application that handles time-related data. In Java, the DateTimeFormatter class provides a powerful and flexible way to convert LocalDate objects into human-readable strings. This is especially useful when you need to display dates in specific formats for users, reports, or data exports. By defining a pattern, you can control exactly how a date appears—whether it's a standard ISO format, a short numeric version, or a more descriptive full-text style.

Main.java


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package com.example;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        LocalDate date = LocalDate.of(2024, 6, 15);
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");
        String formattedDate = date.format(formatter);
        System.out.println("Formatted date: " + formattedDate);
    }
}

When formatting dates, the pattern string you provide to DateTimeFormatter determines the output. Some common patterns include:

"yyyy-MM-dd";
"dd/MM/yyyy";
"MMM dd, yyyy";
"MMMM dd, yyyy".

Choosing the right pattern is important for clarity and consistency. Always consider your audience: for example, "MM/dd/yyyy" is common in the United States, while "dd/MM/yyyy" is more familiar in Europe. To avoid confusion, pick a single date format for your application and use it everywhere. This not only improves usability but also helps prevent errors when parsing or comparing dates.

Main.java


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package com.example;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        LocalDate date = LocalDate.of(2024, 6, 15);
        DateTimeFormatter isoFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        DateTimeFormatter readableFormatter = DateTimeFormatter.ofPattern("MMM dd, yyyy");
        DateTimeFormatter fullMonthFormatter = DateTimeFormatter.ofPattern("MMMM dd, yyyy");

        System.out.println("ISO: " + date.format(isoFormatter));
        System.out.println("Readable: " + date.format(readableFormatter));
        System.out.println("Full Month: " + date.format(fullMonthFormatter));
    }
}

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Avsnitt 3. Kapitel 2

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Suggested prompts:

What are some examples of using DateTimeFormatter in Java?

Can you explain how to create a custom date format?

Why is it important to use consistent date formats in an application?

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Main.java


              1234567891011121314
            
package com.example;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        LocalDate date = LocalDate.of(2024, 6, 15);
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");
        String formattedDate = date.format(formatter);
        System.out.println("Formatted date: " + formattedDate);
    }
}

When formatting dates, the pattern string you provide to DateTimeFormatter determines the output. Some common patterns include:

"yyyy-MM-dd";
"dd/MM/yyyy";
"MMM dd, yyyy";
"MMMM dd, yyyy".

Main.java


              123456789101112131415161718
            
package com.example;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        LocalDate date = LocalDate.of(2024, 6, 15);
        DateTimeFormatter isoFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        DateTimeFormatter readableFormatter = DateTimeFormatter.ofPattern("MMM dd, yyyy");
        DateTimeFormatter fullMonthFormatter = DateTimeFormatter.ofPattern("MMMM dd, yyyy");

        System.out.println("ISO: " + date.format(isoFormatter));
        System.out.println("Readable: " + date.format(readableFormatter));
        System.out.println("Full Month: " + date.format(fullMonthFormatter));
    }
}

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 2

Formatting Dates with DateTimeFormatter

1. What is the result of formatting a LocalDate with the pattern "MMMM dd, yyyy"?

2. Why is it important to use consistent date formats in applications?

3. Which method is used to format a LocalDate with a DateTimeFormatter?

Formatting Dates with DateTimeFormatter

1. What is the result of formatting a LocalDate with the pattern "MMMM dd, yyyy"?

2. Why is it important to use consistent date formats in applications?

3. Which method is used to format a LocalDate with a DateTimeFormatter?