Convert Date to String and String to Date in Java

🎉 Java Date Shenanigans! 🎉

Time flies when you're having fun, but in Java, you need some serious tricks to handle it! Let's dive into the magical world of java.util.Date and learn how to create, format, parse, and manipulate dates like a true time wizard! 🧙‍♂️

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⏳ 1. Formatting a Date to String

Java's SimpleDateFormat lets you turn a Date into a beautifully formatted string. But beware! It's not thread-safe, so don't go sharing it recklessly. 😱

SimpleDateFormat sdf = new SimpleDateFormat("dd/M/yyyy");
String date = sdf.format(new Date());

🛠 Common Date Patterns

Pattern	Example
yyyy-MM-dd (ISO)	"2018-07-14"
dd-MMM-yyyy	"14-Jul-2018"
dd/MM/yyyy	"14/07/2018"
E, MMM dd yyyy	"Sat, Jul 14 2018"
h:mm a	"12:08 PM"
yyyy-MM-dd'T'HH:mm:ssZ	"2018-07-14T14:31:30+0530"

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🔍 2. Parsing a String to Date

Ever received a date as a string and wondered how to turn it into a real date? SimpleDateFormat.parse() to the rescue! 🦸‍♂️

SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
String dateInString = "15-10-2015 10:20:56";
Date date = sdf.parse(dateInString);

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⏰ 3. Getting Current Date and Time

Want to know what time it is? Java's Date class has your back! 😎

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date));

Since Java 8, we have fancier options like LocalDate and LocalTime:

LocalDate today = LocalDate.now();
System.out.println("Today's Local date : " + today);

LocalTime time = LocalTime.now();
System.out.println("Local time now : " + time);

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🔄 4. Convert between Date and Calendar

📅 4.1. Calendar to Date

Calendar calendar = Calendar.getInstance();
Date date = calendar.getTime();

🕰 4.2. Date to Calendar

SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
String dateInString = "27-04-2016 10:22:56";
Date date = sdf.parse(dateInString);

Calendar calendar = Calendar.getInstance();
calendar.setTime(date);

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⚖️ 5. Comparing Two Dates

Time to settle the "who's older" debate! The compareTo() method can tell if one date is before, after, or the same as another. 🤔

Date date1 = new Date();
Date date2 = new Date();

int comparison = date1.compareTo(date2);

Result	Meaning
0	Both dates are identical! 🤝
< 0	date1 is before date2 ⏪
> 0	date1 is after date2 ⏩

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📆 6. Extracting Days, Months, and Years

Need to pull apart a date and get specific components? Calendar has you covered! 🗓️

Calendar calendar = Calendar.getInstance();
calendar.setTime(new Date());

int year       = calendar.get(Calendar.YEAR);
int month      = calendar.get(Calendar.MONTH); // Jan = 0, not 1 😲
int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH);
int dayOfWeek  = calendar.get(Calendar.DAY_OF_WEEK);
int hourOfDay  = calendar.get(Calendar.HOUR_OF_DAY);
int minute     = calendar.get(Calendar.MINUTE);
int second     = calendar.get(Calendar.SECOND);

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🎊 Conclusion

Java’s date handling might seem tricky at first, but once you get the hang of it, you’ll be a Date-Time Ninja! 🥷 Keep practicing, and remember: Never trust SimpleDateFormat in a multithreaded environment! 😅

Happy Learning & Happy Coding! 🚀