BAEL-7614 sql.Timestamp to java.util.Calendar conversion

core-java-modules/core-java-date-operations-4/src/main/java/com/baeldung/timestamptocalendar/SqlTimestampToCalendarConverter.java

@@ -0,0 +1,26 @@
+package com.baeldung.timestamptocalendar;
+
+import java.sql.Timestamp;
+import java.time.Instant;
+import java.util.Calendar;
+
+public class SqlTimestampToCalendarConverter {
+
+    public static void main(String... args) {
+        Timestamp timestamp = new Timestamp(124, 3, 19, 9, 30, 0, 801789562);
+        Calendar calendar = timestampToCalendar(timestamp);
+        System.out.println(calendar.getTime());
+        Instant instant = timestampToInstant(timestamp);
+        System.out.println(instant);
+    }
+
+    public static Calendar timestampToCalendar(Timestamp timestamp) {
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTimeInMillis(timestamp.getTime());
+        return calendar;
+    }
+
+    public static Instant timestampToInstant(Timestamp timestamp) {
+        return timestamp.toInstant();
+    }
+}

core-java-modules/core-java-date-operations-4/src/test/java/com/baeldung/timestamptocalendar/SqlTimestampToCalendarConverterTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.timestamptocalendar;
+
+import static org.junit.Assert.assertEquals;
+
+import java.sql.Timestamp;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.util.Calendar;
+
+import org.junit.Test;
+
+public class SqlTimestampToCalendarConverterTest {
+
+    @Test
+    public void whenConvert_thenEqualMillis() {
+        Timestamp timestamp = new Timestamp(124, 3, 19, 9, 30, 0, 801789562);
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTimeInMillis(timestamp.getTime());
+        assertEquals(calendar.getTimeInMillis(), timestamp.getTime());
+        System.out.println(timestamp);// 2024-04-19 09:30:00.801789562
+        timestamp.setTime(calendar.getTimeInMillis());
+        System.out.println(timestamp);// 2024-04-19 09:30:00.801
+    }
+
+    @Test
+    public void whenConvert_thenEqualNanos() {
+        Timestamp timestamp = new Timestamp(124, 3, 19, 9, 30, 0, 801789562);
+        Instant instantNoTZ = timestamp.toInstant();
+        Instant instantTZ = timestamp.toInstant().atZone(ZoneId.systemDefault()).toInstant();
+        assertEquals(instantNoTZ.getEpochSecond(), instantTZ.getEpochSecond());
+        assertEquals(instantNoTZ.getNano(), instantTZ.getNano());
+    }
+}