[BAEL-6593] - Initial push after adding epoch time to localdate and localdatetime conversions (#14556)

Co-authored-by: bobby00 <edwarobert6@gmail.com>

core-java-modules/core-java-datetime-conversion/src/main/java/com/baeldung/epochtolocaldate/EpochTimeToLocalDateConverter.java

@@ -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;
+    }
+}

core-java-modules/core-java-datetime-conversion/src/main/java/com/baeldung/epochtolocaldate/EpochTimeToLocalDateTimeConverter.java

@@ -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;
+    }
+}

core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/epochtolocaldate/EpochTimeToLocalDateConverterUnitTest.java

@@ -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);
+    }
+}

core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/epochtolocaldate/EpochTimeToLocalDateTimeConverterUnitTest.java

@@ -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, 12, 13, 51);
+
+        Instant instant = Instant.ofEpochMilli(epochTimeMillis);
+        ZoneId zoneId = ZoneId.systemDefault();
+        LocalDateTime actualDateTime = instant.atZone(zoneId).toLocalDateTime();
+
+        assertEquals(expectedDateTime, actualDateTime);
+    }
+
+}