The Java Calendar-API

The java.util.Calendar class in Java is a legacy class that provides utility methods for working with dates and times. It is part of the Java Date-Time API, which is a new API introduced in Java 8 that replaces the legacy java.util.Date class.

Here are some examples of using the java.util.Calendar class to work with dates and times in Java:

import java.util.Calendar;

public class Main {
    public static void main(String[] args) {
        // Get the current date and time
        Calendar calendar = Calendar.getInstance();
        System.out.println(calendar.getTime());

        // Set a specific date and time
        calendar.set(Calendar.YEAR, 2020);
        calendar.set(Calendar.MONTH, Calendar.JANUARY);
        calendar.set(Calendar.DAY_OF_MONTH, 1);
        calendar.set(Calendar.HOUR_OF_DAY, 12);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        System.out.println(calendar.getTime());

        // Add a specific amount of time to a date and time
        calendar.add(Calendar.YEAR, 1);
        calendar.add(Calendar.MONTH, 3);
        calendar.add(Calendar.DAY_OF_MONTH, 10);
        System.out.println(calendar.getTime());
    }
}

In this example, the Calendar.getInstance method is used to get the current date and time, and the set method is used to set a specific date and time. The add method is used to add a specific amount of time to a date and time. The getTime method is used to get the date and time represented by a Calendar object as a java.util.Date object.

Note that the java.util.Calendar class is a legacy class and is not the recommended way of working with dates and times in Java. It is recommended to use the java.time package instead, which provides a more comprehensive and easy-to-use set of classes for working with dates, times, and durations.