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BAEL-5925 Code for the finding max date in object list article

This commit is contained in:
thibault.faure 2022-11-06 12:22:39 +01:00
parent d0c3a7dfd6
commit 2e126e794c
4 changed files with 192 additions and 0 deletions
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50
core-java-modules/core-java-streams-4/src/main/java/com/baeldung/streams/maxdate/DateHelper.java Normal file
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package com.baeldung.streams.maxdate;
import java.time.LocalDate;
import java.util.Comparator;
import java.util.Date;
import java.util.List;
public class DateHelper {
static final Date findMaxDateOf(List<Event> events) {
if (events == null || events.isEmpty()) {
return null;
}
return events.stream()
.map(Event::getDate)
.max(Date::compareTo)
.get();
}
static final Date findMaxDateOfWithComparator(List<Event> events) {
if (events == null || events.isEmpty()) {
return null;
}
return events.stream()
.map(Event::getDate)
.max(Comparator.naturalOrder())
.get();
}
static final LocalDate findMaxDateOfLocalEvents(List<LocalEvent> events) {
if (events == null || events.isEmpty()) {
return null;
}
return events.stream()
.map(LocalEvent::getDate)
.max(LocalDate::compareTo)
.get();
}
static final LocalDate findMaxDateOfLocalEventsWithComparator(List<LocalEvent> events) {
if (events == null || events.isEmpty()) {
return null;
}
return events.stream()
.map(LocalEvent::getDate)
.max(Comparator.naturalOrder())
.get();
}
}

17
core-java-modules/core-java-streams-4/src/main/java/com/baeldung/streams/maxdate/Event.java Normal file
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package com.baeldung.streams.maxdate;
import java.util.Date;
public class Event {
Date date;
public Event(Date date) {
this.date = date;
}
public Date getDate() {
return date;
}
}

16
core-java-modules/core-java-streams-4/src/main/java/com/baeldung/streams/maxdate/LocalEvent.java Normal file
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package com.baeldung.streams.maxdate;
import java.time.LocalDate;
public class LocalEvent {
LocalDate date;
public LocalEvent(LocalDate date) {
this.date = date;
}
public LocalDate getDate() {
return date;
}
}

109
core-java-modules/core-java-streams-4/src/test/java/com/baeldung/streams/maxdate/DateHelperUnitTest.java Normal file
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package com.baeldung.streams.maxdate;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNull;
import java.time.LocalDate;
import java.util.Date;
import java.util.List;
import org.apache.commons.lang3.time.DateUtils;
import org.junit.jupiter.api.Test;
class DateHelperUnitTest {
Date TODAY = new Date();
Event TODAYS_EVENT = new Event(TODAY);
Date TOMORROW = DateUtils.addDays(TODAY, 1);
Event TOMORROWS_EVENT = new Event(TOMORROW);
Date NEXT_WEEK = DateUtils.addDays(TODAY, 7);
Event NEXT_WEEK_EVENT = new Event(NEXT_WEEK);
LocalDate TODAY_LOCAL = LocalDate.now();
LocalEvent TODAY_LOCAL_EVENT = new LocalEvent(TODAY_LOCAL);
LocalDate TOMORROW_LOCAL = TODAY_LOCAL.plusDays(1);
LocalEvent TOMORROW_LOCAL_EVENT = new LocalEvent(TOMORROW_LOCAL);
LocalDate NEXT_WEEK_LOCAL = TODAY_LOCAL.plusWeeks(1);
LocalEvent NEXT_WEEK_LOCAL_EVENT = new LocalEvent(NEXT_WEEK_LOCAL);
@Test
void givenNullEventList_WhenFindMaxDateOf_ThenNull() {
assertNull(DateHelper.findMaxDateOf(null));
}
@Test
void givenEmptyEventList_WhenFindMaxDateOf_ThenNull() {
assertNull(DateHelper.findMaxDateOf(List.of()));
}
@Test
void givenSingleElementEventList_WhenFindMaxDateOf_ThenReturnElementDate() {
assertEquals(TODAY, DateHelper.findMaxDateOf(List.of(TODAYS_EVENT)));
}
@Test
void givenEventList_WhenFindMaxDateOf_ThenReturnMaxDate() {
assertEquals(NEXT_WEEK, DateHelper.findMaxDateOf(List.of(TODAYS_EVENT, TOMORROWS_EVENT, NEXT_WEEK_EVENT)));
}
@Test
void givenNullEventList_WhenFindMaxDateOfWithComparator_ThenNull() {
assertNull(DateHelper.findMaxDateOfWithComparator(null));
}
@Test
void givenEmptyEventList_WhenFindMaxDateOfWithComparator_ThenNull() {
assertNull(DateHelper.findMaxDateOfWithComparator(List.of()));
}
@Test
void givenSingleElementEventList_WhenFindMaxDateOfWithComparator_ThenReturnElementDate() {
assertEquals(TODAY, DateHelper.findMaxDateOfWithComparator(List.of(TODAYS_EVENT)));
}
@Test
void givenEventList_WhenFindMaxDateOfWithComparator_ThenReturnMaxDate() {
assertEquals(NEXT_WEEK, DateHelper.findMaxDateOfWithComparator(List.of(TODAYS_EVENT, TOMORROWS_EVENT, NEXT_WEEK_EVENT)));
}
@Test
void givenNullLocalEventList_WhenFindMaxDateOfLocalEvents_ThenNull() {
assertNull(DateHelper.findMaxDateOfLocalEvents(null));
}
@Test
void givenEmptyLocalEventList_WhenFindMaxDateOfLocalEvents_ThenNull() {
assertNull(DateHelper.findMaxDateOfLocalEvents(List.of()));
}
@Test
void givenSingleElementLocalEventList_WhenFindMaxDateOfLocalEvents_ThenReturnElementDate() {
assertEquals(TODAY_LOCAL, DateHelper.findMaxDateOfLocalEvents(List.of(TODAY_LOCAL_EVENT)));
}
@Test
void givenLocalEventList_WhenFindMaxDateOfLocalEvents_ThenReturnMaxDate() {
assertEquals(NEXT_WEEK_LOCAL, DateHelper.findMaxDateOfLocalEvents(List.of(TODAY_LOCAL_EVENT, TOMORROW_LOCAL_EVENT, NEXT_WEEK_LOCAL_EVENT)));
}
@Test
void givenNullLocalEventList_WhenFindMaxDateOfLocalEventsWithComparator_ThenNull() {
assertNull(DateHelper.findMaxDateOfLocalEventsWithComparator(null));
}
@Test
void givenEmptyLocalEventList_WhenFindMaxDateOfLocalEventsWithComparator_ThenNull() {
assertNull(DateHelper.findMaxDateOfLocalEventsWithComparator(List.of()));
}
@Test
void givenSingleElementLocalEventList_WhenFindMaxDateOfLocalEventsWithComparator_ThenReturnElementDate() {
assertEquals(TODAY_LOCAL, DateHelper.findMaxDateOfLocalEventsWithComparator(List.of(TODAY_LOCAL_EVENT)));
}
@Test
void givenLocalEventList_WhenFindMaxDateOfLocalEventsWithComparator_ThenReturnMaxDate() {
assertEquals(NEXT_WEEK_LOCAL, DateHelper.findMaxDateOfLocalEventsWithComparator(List.of(TODAY_LOCAL_EVENT, TOMORROW_LOCAL_EVENT, NEXT_WEEK_LOCAL_EVENT)));
}
}