Merge remote-tracking branch 'Baeldung/master' into active_mq

# Conflicts: # .gitignore # LICENSE # README.md # core-java-modules/README.md # core-java-modules/core-java-11/README.md # core-java-modules/core-java-11/pom.xml # core-java-modules/core-java-8/README.md # core-java-modules/core-java-8/pom.xml # core-java-modules/core-java-8/src/main/resources/logback.xml # core-java-modules/core-java-annotations/README.md # core-java-modules/core-java-annotations/pom.xml # core-java-modules/core-java-collections-2/README.md # core-java-modules/core-java-collections-2/pom.xml # core-java-modules/core-java-collections-3/README.md # core-java-modules/core-java-collections-3/pom.xml # core-java-modules/core-java-collections-conversions-2/README.md # core-java-modules/core-java-collections-conversions-2/pom.xml # core-java-modules/core-java-collections-conversions/README.md # core-java-modules/core-java-collections-conversions/pom.xml # core-java-modules/core-java-collections-list/README.md # core-java-modules/core-java-collections-list/pom.xml # core-java-modules/core-java-collections/pom.xml # core-java-modules/core-java-datetime-conversion/README.md # core-java-modules/core-java-datetime-conversion/pom.xml # core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/datetime/ConvertInstantToTimestampUnitTest.java # core-java-modules/core-java-io-2/pom.xml # core-java-modules/core-java-io/README.md # core-java-modules/core-java-io/pom.xml # core-java-modules/core-java-io/src/test/resources/fileTest.txt # core-java-modules/core-java-io/src/test/resources/sampleTextFile.txt # core-java-modules/core-java-lambdas/README.md # core-java-modules/core-java-lambdas/pom.xml # core-java-modules/core-java-serialization/pom.xml # core-java-modules/core-java-streams/README.md # core-java-modules/core-java-streams/pom.xml # core-java-modules/core-java-strings/README.md # core-java-modules/core-java-strings/pom.xml # core-java-modules/core-java-strings/src/test/resources/stringtoolong.txt # core-java-modules/core-java-uuid/README.md # core-java-modules/core-java-uuid/pom.xml # core-java-modules/pom.xml # image-processing/README.md # image-processing/pom.xml # image-processing/src/main/java/com/baeldung/imageprocessing/addingtext/AddText.java # image-processing/src/main/java/com/baeldung/imageprocessing/opencv/CameraStream.java # jackson-modules/jackson-annotations/README.md # jackson-modules/jackson-annotations/pom.xml # jackson-modules/jackson-conversions-2/README.md # jackson-modules/jackson-conversions-2/pom.xml # jackson-modules/jackson-conversions/README.md # jackson-modules/jackson-conversions/pom.xml # jackson-modules/jackson-custom-conversions/README.md # jackson-modules/jackson-custom-conversions/pom.xml # jackson-modules/jackson-custom-conversions/src/test/java/com/baeldung/defaultserializercustomserializer/CallingDefaultSerializerUnitTest.java # jackson-modules/jackson-custom-conversions/src/test/java/com/baeldung/deserialization/CustomDeserializationUnitTest.java # jackson-modules/jackson-exceptions/README.md # jackson-modules/jackson-exceptions/pom.xml # jackson-modules/jackson-exceptions/src/test/java/com/baeldung/exceptions/JacksonExceptionsUnitTest.java # jackson-modules/jackson-exceptions/src/test/java/com/baeldung/mappingexception/JacksonMappingExceptionUnitTest.java # jackson-modules/pom.xml # parent-boot-1/pom.xml # parent-boot-2/pom.xml # parent-boot-3/pom.xml # patterns-modules/design-patterns-architectural/pom.xml # patterns-modules/design-patterns-architectural/src/main/java/com/baeldung/repositoryvsdaopattern/UserDaoImpl.java # patterns-modules/design-patterns-behavioral-2/README.md # patterns-modules/design-patterns-behavioral-2/pom.xml # patterns-modules/design-patterns-creational-2/README.md # patterns-modules/design-patterns-creational-2/pom.xml # patterns-modules/design-patterns-singleton/README.md # patterns-modules/design-patterns-structural/src/main/resources/log4jstructuraldp.properties # patterns-modules/enterprise-patterns/pom.xml # patterns-modules/intercepting-filter/pom.xml # patterns-modules/pom.xml # persistence-modules/activejdbc/pom.xml # persistence-modules/hibernate5/README.md # persistence-modules/hibernate5/pom.xml # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/interceptors/CustomInterceptor.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/interceptors/entity/User.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/namingstrategy/CustomPhysicalNamingStrategy.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/persistjson/Customer.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/persistjson/HashMapConverter.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/pojo/OrderEntryIdClass.java # persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/pojo/OrderEntryPK.java # persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/IdentifiersIntegrationTest.java # persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/bootstrap/BootstrapAPIIntegrationTest.java # persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/proxy/HibernateProxyUnitTest.java # persistence-modules/hibernate5/src/test/resources/hibernate-interceptors.properties # persistence-modules/hibernate5/src/test/resources/hibernate-lifecycle.properties # persistence-modules/hibernate5/src/test/resources/hibernate-namingstrategy.properties # persistence-modules/hibernate5/src/test/resources/hibernate-persistjson.properties # persistence-modules/hibernate5/src/test/resources/hibernate.properties # persistence-modules/pom.xml # persistence-modules/spring-data-jpa-crud/pom.xml # persistence-modules/spring-data-jpa-crud/src/main/java/com/baeldung/repository/FruitRepository.java # persistence-modules/spring-data-jpa-repo-2/README.md # persistence-modules/spring-data-jpa-repo-2/pom.xml # persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/model/User.java # persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/repository/CustomUserRepositoryImpl.java # persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/saveperformance/Book.java # persistence-modules/spring-data-jpa-repo-2/src/main/resources/application.properties # persistence-modules/spring-data-mongodb-reactive/pom.xml # persistence-modules/spring-data-redis/README.md # persistence-modules/spring-data-redis/pom.xml # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/reactive/redis/config/RedisConfig.java # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/redis/config/RedisConfig.java # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/redis/model/Student.java # persistence-modules/spring-data-redis/src/main/java/com/baeldung/spring/data/redis/queue/RedisMessageSubscriber.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/reactive/redis/template/RedisKeyCommandsManualTest.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/reactive/redis/template/RedisTemplateListOpsManualTest.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/reactive/redis/template/RedisTemplateValueOpsManualTest.java # persistence-modules/spring-data-redis/src/test/java/com/baeldung/spring/data/redis/repo/StudentRepositoryManualTest.java # pom.xml # testing-modules/assertion-libraries/README.md # testing-modules/assertion-libraries/pom.xml # testing-modules/junit-5-basics/README.md # testing-modules/junit-5-basics/pom.xml # testing-modules/mockito-2/src/main/java/com/baeldung/nullmatcher/Helper.java # testing-modules/mockito-2/src/main/java/com/baeldung/nullmatcher/Main.java # testing-modules/mockito-2/src/main/java/com/baeldung/wantedbutnotinvocked/Helper.java # testing-modules/mockito-2/src/main/java/com/baeldung/wantedbutnotinvocked/Main.java # testing-modules/mockito-2/src/test/java/com/baeldung/nullmatcher/MainUnitTest.java # testing-modules/mockito-2/src/test/java/com/baeldung/wantedbutnotinvocked/MainUnitTest.java # testing-modules/pom.xml # testing-modules/spring-mockito/pom.xml # web-modules/dropwizard/pom.xml # web-modules/jakarta-ee/README.md # web-modules/jakarta-ee/pom.xml # web-modules/jakarta-ee/src/test/java/com/baeldung/eclipse/krazo/UserControllerUnitTest.java # web-modules/java-lite/pom.xml # web-modules/javax-servlets-2/README.md # web-modules/javax-servlets-2/pom.xml # web-modules/javax-servlets/pom.xml # web-modules/jee-7/pom.xml # web-modules/jooby/pom.xml # web-modules/ninja/pom.xml # web-modules/pom.xml # web-modules/ratpack/pom.xml # web-modules/resteasy/pom.xml # web-modules/restx/pom.xml # web-modules/spark-java/pom.xml # web-modules/vraptor/pom.xml # xml/README.md # xml/pom.xml # xml/src/main/resources/customer-binding.xml # xml/src/main/resources/sax/baeldung.xml # xml/src/test/resources/example_default_parser.xml # xml/src/test/resources/example_dom4j.xml # xml/src/test/resources/example_jaxb.xml # xml/src/test/resources/example_jaxen.xml # xml/src/test/resources/example_jdom.xml # xml/src/test/resources/example_stax.xml # xml/src/test/resources/sax/baeldung.xml # xml/src/test/resources/xml/websites.xml # xml/src/test/resources/xml/xee_attribute.xml
2024-04-30 12:23:19 -04:00
parent c18eb6d2ed 8cabe509a5
commit a51b7b55d9
27985 changed files with 1584039 additions and 0 deletions
@@ -0,0 +1,29 @@
+package com.baeldung.epochtolocaldate;
+
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+
+/**
+ * Class which shows a way to convert Epoch time in milliseconds to java.time.LocalDate.
+ * 
+ * @author quincy
+ *
+ */
+
+public class EpochTimeToLocalDateConverter {
+    public static String main(String[] args) {
+        long epochTimeinMillisToConvert = 1624962431000L;
+        
+        Instant instant = Instant.ofEpochMilli(epochTimeinMillisToConvert);
+        
+        ZoneId zoneId = ZoneId.systemDefault(); // Use the system default time zone
+        LocalDate localDate = instant.atZone(zoneId).toLocalDate();
+
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+        String formattedDate = localDate.format(formatter);
+        
+        return formattedDate;
+    }
+}
@@ -0,0 +1,29 @@
+package com.baeldung.epochtolocaldate;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+
+/**
+ * Class which shows a way to convert Epoch time in milliseconds to java.time.LocalDateTime.
+ * 
+ * @author quincy
+ *
+ */
+
+public class EpochTimeToLocalDateTimeConverter {
+    public static String main(String[] args) {
+        long epochTimeinMillisToConvert = 1624962431000L;
+
+        Instant instant = Instant.ofEpochMilli(epochTimeinMillisToConvert);
+        
+        ZoneId zoneId = ZoneId.systemDefault(); // Use the system default time zone
+        LocalDateTime localDateTime = instant.atZone(zoneId).toLocalDateTime();
+
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+        String formattedDate = localDateTime.format(formatter);
+        
+        return formattedDate;
+    }
+}
@@ -0,0 +1,31 @@
+package com.baeldung.timestamptolong;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.Date;
+
+public class TimestampToLong {
+
+    public long usingSimpleDateFormat(String timestampString) throws ParseException {
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+        Date date = sdf.parse(timestampString);
+        String currentDateString = sdf.format(date);
+        return sdf.parse(currentDateString).getTime();
+    }
+
+    public long usingInstantClass(String timestampString) {
+        Instant instant = LocalDateTime.parse(timestampString, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))
+                .atZone(ZoneId.systemDefault())
+                .toInstant();
+        return instant.toEpochMilli();
+    }
+
+    public long usingJava8DateTime(String timestampString) {
+        LocalDateTime localDateTime = LocalDateTime.parse(timestampString.replace(" ", "T"));
+        return localDateTime.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
+    }
+}
@@ -0,0 +1,21 @@
+package com.baeldung.epochtolocaldate;
+
+import org.junit.jupiter.api.Test;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.ZoneId;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class EpochTimeToLocalDateConverterUnitTest {
+    @Test
+    public void testConvertEpochTimeToLocalDate() {
+        long epochTimeMillis = 1624962431000L; // Example epoch time in millisecond
+        LocalDate expectedDate = LocalDate.of(2021, 6, 29);
+
+        Instant instant = Instant.ofEpochMilli(epochTimeMillis);
+        ZoneId zoneId = ZoneId.systemDefault();
+        LocalDate actualDate = instant.atZone(zoneId).toLocalDate();
+
+        assertEquals(expectedDate, actualDate);
+    }
+}
@@ -0,0 +1,24 @@
+package com.baeldung.epochtolocaldate;
+
+import org.junit.jupiter.api.Test;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class EpochTimeToLocalDateTimeConverterUnitTest {
+
+    @Test
+    public void testConvertEpochTimeToLocalDateTime() {
+        long epochTimeMillis = 1624962431000L; // Example epoch time in milliseconds
+        LocalDateTime expectedDateTime = LocalDateTime.of(2021, 6, 29, 10, 27, 11);
+
+        Instant instant = Instant.ofEpochMilli(epochTimeMillis);
+        ZoneId zoneId = ZoneId.of("UTC");
+        LocalDateTime actualDateTime = instant.atZone(zoneId).toLocalDateTime();
+
+        assertEquals(expectedDateTime, actualDateTime);
+    }
+
+}
@@ -0,0 +1,22 @@
+package com.baeldung.jodadatetimetostandarddate;
+
+import org.joda.time.DateTime;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class JodaDateTimeToDateAndViceVersaUnitTest {
+    @Test
+    public void givenJodaDateTime_whenConvertingToJavaDate_thenConversionIsCorrect() {
+        DateTime jodaDateTime = new DateTime();
+        java.util.Date javaDate = jodaDateTime.toDate();
+        assertEquals(jodaDateTime.getMillis(), javaDate.getTime());
+    }
+
+    @Test
+    public void givenJavaDate_whenConvertingToJodaDateTime_thenConversionIsCorrect() {
+        java.util.Date javaDate = new java.util.Date();
+        DateTime jodaDateTime = new DateTime(javaDate);
+        assertEquals(javaDate.getTime(), jodaDateTime.getMillis());
+    }
+}
@@ -0,0 +1,89 @@
+import org.junit.jupiter.api.Test;
+
+import java.time.*;
+
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+
+public class LocalDateTimeToZonedDateTimeUnitTest {
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithAtZoneMethod_shouldConvertAndMaintainDateTimeValues(){
+        LocalDateTime localDateTime = LocalDateTime.of(2022, 1, 1, 0, 30, 22);
+        ZonedDateTime zonedDateTime = localDateTime.atZone(ZoneId.of("Canada/Atlantic"));
+
+        assertEquals(localDateTime.getYear(), zonedDateTime.getYear());
+        assertEquals(localDateTime.getMonth(), zonedDateTime.getMonth());
+        assertEquals(localDateTime.getDayOfMonth(), zonedDateTime.getDayOfMonth());
+        assertEquals(localDateTime.getHour(), zonedDateTime.getHour());
+        assertEquals(localDateTime.getMinute(), zonedDateTime.getMinute());
+        assertEquals(localDateTime.getSecond(), zonedDateTime.getSecond());
+    }
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithAtZoneAndwithZoneSameInstantMethods_shouldConvert(){
+        LocalDateTime localDateTime = LocalDateTime.of(2022, 1, 1, 0, 30, 22);
+        ZonedDateTime zonedDateTime = localDateTime.atZone(ZoneId.of("Africa/Lagos")).withZoneSameInstant(ZoneId.of("Canada/Atlantic"));
+
+        assertEquals("2021-12-31T19:30:22-04:00[Canada/Atlantic]", zonedDateTime.toString());
+        assertEquals("-04:00", zonedDateTime.getOffset().toString());
+    }
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithOfMethod_shouldConvert(){
+        LocalDateTime localDateTime = LocalDateTime.of(2022, 11, 5, 7, 30, 22);
+        ZonedDateTime zonedDateTime = ZonedDateTime.of(localDateTime, ZoneId.of("Africa/Accra")).withZoneSameInstant(ZoneId.of("Africa/Lagos"));
+
+        assertEquals("2022-11-05T08:30:22+01:00[Africa/Lagos]", zonedDateTime.toString());
+        assertEquals(localDateTime.getYear(), zonedDateTime.getYear());
+    }
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithOfInstantMethod_shouldConvert(){
+        LocalDateTime localDateTime = LocalDateTime.of(2022, 1, 5, 17, 30, 22);
+        ZoneId zoneId = ZoneId.of("Africa/Lagos");
+        ZoneOffset zoneOffset = zoneId.getRules().getOffset(localDateTime);
+        ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(localDateTime, zoneOffset, zoneId);
+
+        assertEquals("2022-01-05T17:30:22+01:00[Africa/Lagos]", zonedDateTime.toString());
+    }
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithOfLocalMethod_shouldConvert(){
+        LocalDateTime localDateTime = LocalDateTime.of(2022, 8, 25, 8, 35, 22);
+        ZoneId zoneId = ZoneId.of("Africa/Lagos");
+        ZoneOffset zoneOffset = zoneId.getRules().getOffset(localDateTime);
+        ZonedDateTime zonedDateTime = ZonedDateTime.ofLocal(localDateTime, zoneId, zoneOffset);
+
+        assertEquals("2022-08-25T08:35:22+01:00[Africa/Lagos]", zonedDateTime.toString());
+    }
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithOfStrictMethod_shouldConvert(){
+        LocalDateTime localDateTime = LocalDateTime.of(2002, 12, 25, 6, 18, 2);
+        ZoneId zoneId = ZoneId.of("Asia/Tokyo");
+        ZoneOffset zoneOffset = zoneId.getRules().getOffset(localDateTime);
+        ZonedDateTime zonedDateTime = ZonedDateTime.ofStrict(localDateTime, zoneOffset, zoneId);
+
+        assertEquals("2002-12-25T06:18:02+09:00[Asia/Tokyo]", zonedDateTime.toString());
+    }
+
+    @Test
+    void whenConvertLocalDateTimeToZonedDateTimeWithInvalidZoneOffSet_shouldThrowDateTimeException(){
+        LocalDateTime localDateTime = LocalDateTime.of(2022, 12, 25, 6, 18, 2);;
+        ZoneId zoneId = ZoneId.of("Asia/Tokyo");
+        ZoneOffset zoneOffset = ZoneOffset.UTC;
+        assertThrows(DateTimeException.class, () -> ZonedDateTime.ofStrict(localDateTime, zoneOffset, zoneId));
+    }
+
+
+    @Test
+    void whenConvertZonedDateTimeToLocalDateTimeWithToLocalDateTimeMethod_shouldConvert(){
+        ZonedDateTime zonedDateTime = ZonedDateTime.of(2011, 2, 12, 6, 14, 1, 58086000, ZoneId.of("Asia/Tokyo"));
+        LocalDateTime localDateTime = zonedDateTime.toLocalDateTime();
+
+        assertEquals("2011-02-12T06:14:01.058086+09:00[Asia/Tokyo]", zonedDateTime.toString());
+    }
+}
@@ -0,0 +1,42 @@
+package com.baeldung.timestamptolocaldatetime;
+
+import org.joda.time.DateTimeZone;
+import org.junit.Test;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+
+import org.joda.time.DateTime;
+import org.joda.time.format.DateTimeFormat;
+
+import static org.junit.Assert.assertEquals;
+
+public class TimeToLocalDateTimeUnitTest {
+    private static final long timestampInMillis = 1700010123000L;
+    private static final String expectedTimestampString = "2023-11-15 01:02:03";
+
+    @Test
+    public void givenTimestamp_whenConvertingToLocalDateTime_thenConvertSuccessfully() {
+        Instant instant = Instant.ofEpochMilli(timestampInMillis);
+        LocalDateTime localDateTime =
+                LocalDateTime.ofInstant(instant, ZoneId.of("UTC"));
+
+        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+        String formattedDateTime = localDateTime.format(formatter);
+
+        assertEquals(expectedTimestampString, formattedDateTime);
+    }
+
+    @Test
+    public void givenJodaTime_whenGettingTimestamp_thenConvertToLong() {
+        DateTime dateTime = new DateTime(timestampInMillis, DateTimeZone.UTC);
+        org.joda.time.LocalDateTime localDateTime = dateTime.toLocalDateTime();
+
+        org.joda.time.format.DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");
+        String actualTimestamp = formatter.print(localDateTime);
+
+        assertEquals(expectedTimestampString, actualTimestamp);
+    }
+}
@@ -0,0 +1,43 @@
+package com.baeldung.timestamptolong;
+
+import org.junit.Test;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.Date;
+
+import static org.junit.Assert.assertEquals;
+
+public class TimestampToLongUnitTest {
+    private static final String timestampString = "2023-11-15 01:02:03";
+
+    @Test
+    public void givenSimpleDateFormat_whenFormattingDate_thenConvertToLong() throws ParseException {
+        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
+        Date date = sdf.parse(timestampString);
+
+        String currentDateString = sdf.format(date);
+        long actualTimestamp = sdf.parse(currentDateString).getTime();
+        assertEquals(1700010123000L, actualTimestamp);
+    }
+
+    @Test
+    public void givenInstantClass_whenGettingTimestamp_thenConvertToLong() {
+        Instant instant = LocalDateTime.parse(timestampString, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))
+                .atZone(ZoneId.systemDefault())
+                .toInstant();
+        long actualTimestamp = instant.toEpochMilli();
+        assertEquals(1700010123000L, actualTimestamp);
+    }
+
+    @Test
+    public void givenJava8DateTime_whenGettingTimestamp_thenConvertToLong() {
+        LocalDateTime localDateTime = LocalDateTime.parse(timestampString.replace(" ", "T"));
+        long actualTimestamp = localDateTime.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
+        assertEquals(1700010123000L, actualTimestamp);
+    }
+}
@@ -0,0 +1,30 @@
+package com.baeldung.twelvehourstotwentyhours;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalTime;
+import java.time.format.DateTimeFormatter;
+import java.util.Date;
+import java.util.Locale;
+import org.junit.jupiter.api.Test;
+
+public class TimeConversionUnitTest {
+
+    @Test
+    public void givenTimeInTwelveHours_whenConvertingToTwentyHours_thenConverted() throws ParseException {
+        SimpleDateFormat displayFormat = new SimpleDateFormat("HH:mm");
+        SimpleDateFormat parseFormat = new SimpleDateFormat("hh:mm a");
+        Date date = parseFormat.parse("06:00 PM");
+        assertEquals("18:00", displayFormat.format(date));
+    }
+
+    @Test
+    public void givenTimeInTwelveHours_whenConvertingToTwentyHoursWithDateTimeFormatter_thenConverted() throws ParseException {
+        String time = LocalTime.parse("06:00 PM", DateTimeFormatter.ofPattern("hh:mm a", Locale.US))
+          .format(DateTimeFormatter.ofPattern("HH:mm"));
+        assertEquals("18:00", time);
+    }
+
+}