[BAEL-8456] - Moved Java Date articles into a new module - 'java-dates'

java-dates/src/test/java/com/baeldung/dateapi/ConversionExample.java

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+package com.baeldung.dateapi;
+
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.util.Date;
+import java.util.GregorianCalendar;
+import java.util.TimeZone;
+
+public class ConversionExample {
+    public static void main(String[] args) {
+        Instant instantFromCalendar = GregorianCalendar.getInstance().toInstant();
+        ZonedDateTime zonedDateTimeFromCalendar = new GregorianCalendar().toZonedDateTime();
+        Date dateFromInstant = Date.from(Instant.now());
+        GregorianCalendar calendarFromZonedDateTime = GregorianCalendar.from(ZonedDateTime.now());
+        Instant instantFromDate = new Date().toInstant();
+        ZoneId zoneIdFromTimeZone = TimeZone.getTimeZone("PST").toZoneId();
+    }
+}

java-dates/src/test/java/com/baeldung/dateapi/JavaDurationUnitTest.java

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+package com.baeldung.dateapi;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
+
+import org.junit.Test;
+
+public class JavaDurationUnitTest {
+
+    @Test
+    public void test2() {
+        Instant start = Instant.parse("2017-10-03T10:15:30.00Z");
+        Instant end = Instant.parse("2017-10-03T10:16:30.00Z");
+
+        Duration duration = Duration.between(start, end);
+
+        assertFalse(duration.isNegative());
+
+        assertEquals(60, duration.getSeconds());
+        assertEquals(1, duration.toMinutes());
+
+        Duration fromDays = Duration.ofDays(1);
+        assertEquals(86400, fromDays.getSeconds());
+
+        Duration fromMinutes = Duration.ofMinutes(60);
+        assertEquals(1, fromMinutes.toHours());
+
+        assertEquals(120, duration.plusSeconds(60).getSeconds());
+        assertEquals(30, duration.minusSeconds(30).getSeconds());
+
+        assertEquals(120, duration.plus(60, ChronoUnit.SECONDS).getSeconds());
+        assertEquals(30, duration.minus(30, ChronoUnit.SECONDS).getSeconds());
+
+        Duration fromChar1 = Duration.parse("P1DT1H10M10.5S");
+        Duration fromChar2 = Duration.parse("PT10M");
+    }
+
+}

java-dates/src/test/java/com/baeldung/dateapi/JavaPeriodUnitTest.java

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+package com.baeldung.dateapi;
+
+import org.apache.log4j.Logger;
+import org.junit.Test;
+
+import java.time.LocalDate;
+import java.time.Period;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
+public class JavaPeriodUnitTest {
+
+    private static final Logger LOG = Logger.getLogger(JavaPeriodUnitTest.class);
+
+    @Test
+    public void whenTestPeriod_thenOk() {
+
+        LocalDate startDate = LocalDate.of(2015, 2, 15);
+        LocalDate endDate = LocalDate.of(2017, 1, 21);
+
+        Period period = Period.between(startDate, endDate);
+
+        LOG.info(String.format("Years:%d months:%d days:%d", period.getYears(), period.getMonths(), period.getDays()));
+
+        assertFalse(period.isNegative());
+        assertEquals(56, period.plusDays(50).getDays());
+        assertEquals(9, period.minusMonths(2).getMonths());
+
+        Period fromUnits = Period.of(3, 10, 10);
+        Period fromDays = Period.ofDays(50);
+        Period fromMonths = Period.ofMonths(5);
+        Period fromYears = Period.ofYears(10);
+        Period fromWeeks = Period.ofWeeks(40);
+
+        assertEquals(280, fromWeeks.getDays());
+
+        Period fromCharYears = Period.parse("P2Y");
+        assertEquals(2, fromCharYears.getYears());
+        Period fromCharUnits = Period.parse("P2Y3M5D");
+        assertEquals(5, fromCharUnits.getDays());
+    }
+
+}

java-dates/src/test/java/com/baeldung/dateapi/JavaUtilTimeUnitTest.java

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+package com.baeldung.dateapi;
+
+import org.junit.Test;
+
+import java.text.ParseException;
+import java.time.Duration;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.Month;
+import java.time.YearMonth;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoUnit;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class JavaUtilTimeUnitTest {
+
+    @Test
+    public void currentTime() {
+        final LocalDate now = LocalDate.now();
+
+        System.out.println(now);
+        // there is not much to test here
+    }
+
+    @Test
+    public void specificTime() {
+        LocalDate birthDay = LocalDate.of(1990, Month.DECEMBER, 15);
+
+        System.out.println(birthDay);
+        // there is not much to test here
+    }
+
+    @Test
+    public void extractMonth() {
+        Month month = LocalDate.of(1990, Month.DECEMBER, 15).getMonth();
+
+        assertThat(month).isEqualTo(Month.DECEMBER);
+    }
+
+    @Test
+    public void subtractTime() {
+        LocalDateTime fiveHoursBefore = LocalDateTime.of(1990, Month.DECEMBER, 15, 15, 0).minusHours(5);
+
+        assertThat(fiveHoursBefore.getHour()).isEqualTo(10);
+    }
+
+    @Test
+    public void alterField() {
+        LocalDateTime inJune = LocalDateTime.of(1990, Month.DECEMBER, 15, 15, 0).with(Month.JUNE);
+
+        assertThat(inJune.getMonth()).isEqualTo(Month.JUNE);
+    }
+
+    @Test
+    public void truncate() {
+        LocalTime truncated = LocalTime.of(15, 12, 34).truncatedTo(ChronoUnit.HOURS);
+
+        assertThat(truncated).isEqualTo(LocalTime.of(15, 0, 0));
+    }
+
+    @Test
+    public void getTimeSpan() {
+        LocalDateTime now = LocalDateTime.now();
+        LocalDateTime hourLater = now.plusHours(1);
+        Duration span = Duration.between(now, hourLater);
+
+        assertThat(span).isEqualTo(Duration.ofHours(1));
+    }
+
+    @Test
+    public void formatAndParse() throws ParseException {
+        LocalDate someDate = LocalDate.of(2016, 12, 7);
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+        String formattedDate = someDate.format(formatter);
+        LocalDate parsedDate = LocalDate.parse(formattedDate, formatter);
+
+        assertThat(formattedDate).isEqualTo("2016-12-07");
+        assertThat(parsedDate).isEqualTo(someDate);
+    }
+
+    @Test
+    public void daysInMonth() {
+        int daysInMonth = YearMonth.of(1990, 2).lengthOfMonth();
+
+        assertThat(daysInMonth).isEqualTo(28);
+    }
+}