Merge pull request #4538 from asturcon/tutorials/dateWithoutTime

BAEL-1894 - Date without time

core-java/src/main/java/com/baeldung/date/DateWithoutTime.java

@@ -0,0 +1,30 @@
+package com.baeldung.date;
+
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.time.LocalDate;
+import java.util.Calendar;
+import java.util.Date;
+
+public class DateWithoutTime {
+
+    public static Date getDateWithoutTimeUsingCalendar() {
+        Calendar calendar = Calendar.getInstance();
+        calendar.set(Calendar.HOUR_OF_DAY, 0);
+        calendar.set(Calendar.MINUTE, 0);
+        calendar.set(Calendar.SECOND, 0);
+        calendar.set(Calendar.MILLISECOND, 0);
+
+        return calendar.getTime();
+    }
+
+    public static Date getDateWithoutTimeUsingFormat() throws ParseException {
+        SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
+        return formatter.parse(formatter.format(new Date()));
+    }
+
+    public static LocalDate getLocalDate() {
+        return LocalDate.now();
+    }
+
+}

core-java/src/test/java/com/baeldung/date/DateWithoutTimeUnitTest.java

@@ -0,0 +1,92 @@
+package com.baeldung.date;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.text.ParseException;
+import java.time.LocalDate;
+import java.time.OffsetDateTime;
+import java.util.Calendar;
+import java.util.Date;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class DateWithoutTimeUnitTest {
+
+    private static final long MILLISECONDS_PER_DAY = 24 * 60 * 60 * 1000;
+
+    @Test
+    public void whenGettingDateWithoutTimeUsingCalendar_thenReturnDateWithoutTime() {
+        Date dateWithoutTime = DateWithoutTime.getDateWithoutTimeUsingCalendar();
+
+        // first check the time is set to 0
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(dateWithoutTime);
+
+        assertEquals(0, calendar.get(Calendar.HOUR_OF_DAY));
+        assertEquals(0, calendar.get(Calendar.MINUTE));
+        assertEquals(0, calendar.get(Calendar.SECOND));
+        assertEquals(0, calendar.get(Calendar.MILLISECOND));
+
+        // we get the day of the date
+        int day = calendar.get(Calendar.DAY_OF_MONTH);
+
+        // if we add the mills of one day minus 1 we should get the same day
+        calendar.setTimeInMillis(dateWithoutTime.getTime() + MILLISECONDS_PER_DAY - 1);
+        assertEquals(day, calendar.get(Calendar.DAY_OF_MONTH));
+
+        // if we add one full day in millis we should get a different day
+        calendar.setTimeInMillis(dateWithoutTime.getTime() + MILLISECONDS_PER_DAY);
+        assertNotEquals(day, calendar.get(Calendar.DAY_OF_MONTH));
+    }
+
+    @Test
+    public void whenGettingDateWithoutTimeUsingFormat_thenReturnDateWithoutTime() throws ParseException {
+        Date dateWithoutTime = DateWithoutTime.getDateWithoutTimeUsingFormat();
+
+        // first check the time is set to 0
+        Calendar calendar = Calendar.getInstance();
+        calendar.setTime(dateWithoutTime);
+
+        assertEquals(0, calendar.get(Calendar.HOUR_OF_DAY));
+        assertEquals(0, calendar.get(Calendar.MINUTE));
+        assertEquals(0, calendar.get(Calendar.SECOND));
+        assertEquals(0, calendar.get(Calendar.MILLISECOND));
+
+        // we get the day of the date
+        int day = calendar.get(Calendar.DAY_OF_MONTH);
+
+        // if we add the mills of one day minus 1 we should get the same day
+        calendar.setTimeInMillis(dateWithoutTime.getTime() + MILLISECONDS_PER_DAY - 1);
+        assertEquals(day, calendar.get(Calendar.DAY_OF_MONTH));
+
+        // if we add one full day in millis we should get a different day
+        calendar.setTimeInMillis(dateWithoutTime.getTime() + MILLISECONDS_PER_DAY);
+        assertNotEquals(day, calendar.get(Calendar.DAY_OF_MONTH));
+    }
+
+    @Test
+    public void whenGettingLocalDate_thenReturnDateWithoutTime() {
+        // get the local date
+        LocalDate localDate = DateWithoutTime.getLocalDate();
+
+        // get the millis of our LocalDate
+        long millisLocalDate = localDate
+          .atStartOfDay()
+          .toInstant(OffsetDateTime
+            .now()
+            .getOffset())
+          .toEpochMilli();
+
+        Calendar calendar = Calendar.getInstance();
+        // if we add the millis of one day minus 1 we should get the same day
+        calendar.setTimeInMillis(millisLocalDate + MILLISECONDS_PER_DAY - 1);
+        assertEquals(localDate.getDayOfMonth(), calendar.get(Calendar.DAY_OF_MONTH));
+
+        // if we add one full day in millis we should get a different day
+        calendar.setTimeInMillis(millisLocalDate + MILLISECONDS_PER_DAY);
+        assertNotEquals(localDate.getDayOfMonth(), calendar.get(Calendar.DAY_OF_MONTH));
+    }
+
+}