[BAEL-18364] move spring-rest-*** articles - 1

java-dates/src/test/java/com/baeldung/datetime/ConvertInstantToTimestampUnitTest.java

@@ -0,0 +1,30 @@
+package com.baeldung.datetime;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.sql.Timestamp;
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.util.TimeZone;
+
+import org.junit.Test;
+
+public class ConvertInstantToTimestampUnitTest {
+
+    @Test
+    public void givenInstant_whenConvertedToTimestamp_thenGetTimestampWithSamePointOnTimeline() {
+        Instant instant = Instant.now();
+        Timestamp timestamp = Timestamp.from(instant); // same point on the time-line as Instant
+        assertThat(instant.toEpochMilli()).isEqualTo(timestamp.getTime());
+
+        instant = timestamp.toInstant();
+        assertThat(instant.toEpochMilli()).isEqualTo(timestamp.getTime());
+
+        DateFormat df = DateFormat.getDateTimeInstance();
+        df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SS'Z'");
+        df.setTimeZone(TimeZone.getTimeZone("UTC"));
+        assertThat(instant.toString()).isEqualTo(df.format(timestamp).toString());
+    }
+}