How Can I Convert a Java Calendar Date to yyyy-MM-dd Format?

Convert Calendar Date to yyyy-MM-dd Format in Java

Problem:

Converting a Calendar date to the commonly used yyyy-MM-dd format is essential for various applications, including data validation and database operations. However, the default Java Date object does not provide a direct method to obtain this format.

Solution:

To achieve this conversion, one can leverage the formatting capabilities of Java. Here are two approaches:

1. Using SimpleDateFormat (Java 7 and earlier):

Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, 1);
SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
String date1 = format1.format(cal.getTime());

This solution utilizes SimpleDateFormat to parse and format the Date object into the desired format.

2. Using LocalDateTime (Java 8 and later):

LocalDateTime ldt = LocalDateTime.now().plusDays(1);
DateTimeFormatter format1 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
String formatter = format1.format(ldt);

With Java 8 and later, LocalDateTime provides an alternative method for date manipulation. DateTimeFormatter can be used to format the date into the required format.

Note:

• The formatted date can be used for comparison purposes in Hibernate criteriaqueries.
• Java Dates represent milliseconds since January 1, 1970, 00:00:00 GMT, while the formatted version is solely a string representation of the date in the specified format.
• Prior to Java 8, the ThreeTen Backport can be used for similar functionality.

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