Merge pull request #4579 from amitabhmandal/BAEL-1896

BAEL-1896: Guide to GregorianCalendar

core-java/src/main/java/com/baeldung/gregorian/calendar/GregorianCalendarExample.java

@@ -0,0 +1,69 @@
+package com.baeldung.gregorian.calendar;
+
+import java.time.format.DateTimeFormatter;
+import java.util.Calendar;
+import java.util.Collections;
+import java.util.Date;
+import java.util.GregorianCalendar;
+import java.util.HashSet;
+import java.util.Locale;
+import java.util.Set;
+import java.util.TimeZone;
+
+import javax.xml.datatype.DatatypeConfigurationException;
+import javax.xml.datatype.DatatypeFactory;
+import javax.xml.datatype.XMLGregorianCalendar;
+
+public class GregorianCalendarExample {
+
+   
+    public Date setMonth(GregorianCalendar calendar, int amount) {
+        calendar.set(Calendar.MONTH, amount);
+        return calendar.getTime();
+    }
+
+   
+    public Date rollAdd(GregorianCalendar calendar, int amount) {
+        calendar.roll(GregorianCalendar.MONTH, amount);
+        return calendar.getTime();
+    }
+
+    public  boolean isLeapYearExample(int year) {
+        GregorianCalendar cal = (GregorianCalendar) GregorianCalendar.getInstance();
+        return cal.isLeapYear(year);
+    }
+
+
+
+    public Date subtractDays(GregorianCalendar calendar, int daysToSubtract) {
+        GregorianCalendar cal = calendar;
+        cal.add(Calendar.DATE, -daysToSubtract);
+        return cal.getTime();
+    }
+
+    public Date addDays(GregorianCalendar calendar, int daysToAdd) {
+        GregorianCalendar cal = calendar;
+        cal.add(Calendar.DATE, daysToAdd);
+        return cal.getTime();
+    }
+
+    public XMLGregorianCalendar toXMLGregorianCalendar(GregorianCalendar calendar) throws DatatypeConfigurationException {
+        DatatypeFactory datatypeFactory = DatatypeFactory.newInstance();
+        return datatypeFactory.newXMLGregorianCalendar(calendar);
+    }
+
+    public Date toDate(XMLGregorianCalendar calendar) {
+        return calendar.toGregorianCalendar()
+            .getTime();
+    }
+
+    public int compareDates(GregorianCalendar firstDate, GregorianCalendar secondDate) {
+        return firstDate.compareTo(secondDate);
+    }
+
+    public String formatDate(GregorianCalendar calendar) {
+        return calendar.toZonedDateTime()
+            .format(DateTimeFormatter.ofPattern("d MMM uuuu"));
+    }
+
+}