BAEL-3911 (#8939)

* Initial version of the code.

* Addressed PR comment.

core-java-modules/core-java-date-operations-2/src/main/java/com/baeldung/datetime/dayofweek/DayOfWeekExtractor.java

@@ -0,0 +1,35 @@
+package com.baeldung.datetime.dayofweek;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.time.DayOfWeek;
+import java.time.LocalDate;
+import java.time.format.TextStyle;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.Locale;
+
+public class DayOfWeekExtractor {
+
+    public static int getDayNumberOld(Date date) {
+        Calendar cal = Calendar.getInstance();
+        cal.setTime(date);
+        return cal.get(Calendar.DAY_OF_WEEK);
+    }
+    
+    public static String getDayStringOld(Date date, Locale locale ) {
+        DateFormat formatter = new SimpleDateFormat("EEEE", locale);
+        return formatter.format(date);
+    }
+
+    public static int getDayNumberNew(LocalDate date) {
+        DayOfWeek day = date.getDayOfWeek();
+        return day.getValue();
+    }
+
+    public static String getDayStringNew(LocalDate date, Locale locale ) {
+        DayOfWeek day = date.getDayOfWeek();
+        return day.getDisplayName(TextStyle.FULL, locale);
+    }
+    
+}

core-java-modules/core-java-date-operations-2/src/test/java/com/baeldung/datetime/dayofweek/DayOfWeekExtractorUnitTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.datetime.dayofweek;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.text.DateFormat;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.util.Calendar;
+import java.util.Locale;
+
+import org.junit.Test;
+
+public class DayOfWeekExtractorUnitTest {
+    
+    private DateFormat oldDateParser = new SimpleDateFormat("yyyy-MM-dd"); 
+
+    @Test
+    public void givenFeb29_2020_thenOldSaturdayNumber() throws ParseException {
+        assertThat(DayOfWeekExtractor.getDayNumberOld(oldDateParser.parse("2020-02-29")) == Calendar.SATURDAY);
+    }
+
+    @Test
+    public void givenFeb29_2020_and_localeUS_thenOldSaturdayText() throws ParseException {
+        assertThat("Saturday".equals(DayOfWeekExtractor.getDayStringOld(oldDateParser.parse("2020-02-29"), Locale.US)) );
+    }
+
+    @Test
+    public void givenFeb29_2020_and_localeDE_thenOldSaturdayText() throws ParseException {
+        assertThat("Samstag".equals(DayOfWeekExtractor.getDayStringOld(oldDateParser.parse("2020-02-29"), Locale.GERMANY)) );
+    }
+
+    @Test
+    public void givenFeb29_2020_thenNewSaturdayNumber() throws ParseException {
+        assertThat(DayOfWeekExtractor.getDayNumberNew(LocalDate.parse("2020-02-29")) == Calendar.SATURDAY);
+    }
+
+    @Test
+    public void givenFeb29_2020_and_localeUS_thenNewSaturdayText() throws ParseException {
+        assertThat("Saturday".equals(DayOfWeekExtractor.getDayStringOld(oldDateParser.parse("2020-02-29"), Locale.US)) );
+    }
+
+    @Test
+    public void givenFeb29_2020_and_localeDE_thenNewSaturdayText() throws ParseException {
+        assertThat("Samstag".equals(DayOfWeekExtractor.getDayStringOld(oldDateParser.parse("2020-02-29"), Locale.GERMANY)) );
+    }
+
+
+}
+
+
+