Add example for java.time.Period

src/main/java/io/javaalmanac/snippets/time/HowOldIsJava.java

@@ -0,0 +1,39 @@
+package io.javaalmanac.snippets.time;
+
+import java.time.LocalDate;
+import java.time.Period;
+import java.time.ZoneId;
+
+/**
+ * A date-based amount of time can be represented with the
+ * {@link java.time.Period} type. With this data type a time span is expressed
+ * as a number of years, months and days.
+ * 
+ * @title Time Period
+ * @category api.time
+ * @since 8
+ */
+public class HowOldIsJava {
+
+	static final LocalDate BIRTHDAY_OF_JAVA = LocalDate.of(1995, 5, 23);
+
+	static final ZoneId TIMEZONE_OF_BIRTH = ZoneId.of("America/Los_Angeles");
+
+	public static void main(String[] args) {
+
+		var today = LocalDate.now(TIMEZONE_OF_BIRTH);
+		var age = Period.between(BIRTHDAY_OF_JAVA, today);
+		System.out.println("As of today Java is %s old".formatted(fmt(age)));
+
+		var nextAnivesary = BIRTHDAY_OF_JAVA.plus(Period.ofYears(age.getYears() + 1));
+		var tillAnivesary = Period.between(today, nextAnivesary);
+		System.out.println("Java's next birthday is in %s".formatted(fmt(tillAnivesary)));
+
+	}
+
+	static String fmt(Period p) {
+		// Unfortunately there is no built-in formatter for Period objects
+		return "%d years, %d months and %d days".formatted(p.getYears(), p.getMonths(), p.getDays());
+	}
+
+}