Conversion From 12 Hours Time to 24 Hours Time in Java (#14580)

core-java-modules/core-java-datetime-conversion/src/test/java/com/baeldung/twelvehourstotwentyhours/TimeConversionUnitTest.java

@@ -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);
+    }
+
+}