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‎src/io/vakin/java8/ConcurrentHashMapForEach.java

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package io.vakin.java8;
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import java.util.UUID;
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import java.util.concurrent.ConcurrentHashMap;
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public class ConcurrentHashMapForEach {
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public static void main(String[] args) {
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ConcurrentHashMap<Integer, UUID> concurrentHashMap = new ConcurrentHashMap<>();
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for (int i = 0; i < 100; i++) {
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concurrentHashMap.put(i, UUID.randomUUID());
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}
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int threshold = 1;
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concurrentHashMap.forEachValue(threshold, System.out::println);
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concurrentHashMap.forEach((id, uuid) -> {
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if (id % 10 == 0) {
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System.out.println(String.format("%s: %s", id, uuid));
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}
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});
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UUID searchResult = concurrentHashMap.search(threshold, (id, uuid) -> {
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if (String.valueOf(uuid).startsWith(String.valueOf(id))) {
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return uuid;
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}
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return null;
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});
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System.out.println(searchResult);
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}
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}

‎src/io/vakin/java8/NioFileTest.java

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package io.vakin.java8;
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import java.io.BufferedReader;
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import java.io.BufferedWriter;
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import java.io.IOException;
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import java.nio.file.Files;
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import java.nio.file.Path;
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import java.nio.file.Paths;
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import java.util.List;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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public class NioFileTest {
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public static void main(String[] args) throws IOException {
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testWalk();
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testFind();
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testList();
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testLines();
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testReader();
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testWriter();
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testReadWriteLines();
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testReaderLines();
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}
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private static void testReaderLines() throws IOException {
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Path path = Paths.get("res/readme.txt");
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try (BufferedReader reader = Files.newBufferedReader(path)) {
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long countPrints = reader
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.lines()
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.filter(line -> line.contains("print"))
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.count();
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System.out.println(countPrints);
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}
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}
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private static void testWriter() throws IOException {
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Path path = Paths.get("res/output.txt");
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try (BufferedWriter writer = Files.newBufferedWriter(path)) {
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writer.write("print('Hello World');");
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}
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}
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private static void testReader() throws IOException {
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Path path = Paths.get("res/readme.txt");
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try (BufferedReader reader = Files.newBufferedReader(path)) {
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System.out.println(reader.readLine());
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}
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}
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private static void testWalk() throws IOException {
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Path start = Paths.get("");
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int maxDepth = 5;
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try (Stream<Path> stream = Files.walk(start, maxDepth)) {
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String joined = stream
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.map(String::valueOf)
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.filter(path -> path.endsWith(".txt"))
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.collect(Collectors.joining("; "));
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System.out.println("walk(): " + joined);
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}
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}
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private static void testFind() throws IOException {
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Path start = Paths.get("");
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int maxDepth = 5;
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try (Stream<Path> stream = Files.find(start, maxDepth, (path, attr) ->
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String.valueOf(path).endsWith(".txt"))) {
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String joined = stream
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.sorted()
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.map(String::valueOf)
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.collect(Collectors.joining("; "));
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System.out.println("find(): " + joined);
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}
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}
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private static void testList() throws IOException {
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try (Stream<Path> stream = Files.list(Paths.get(""))) {
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String joined = stream
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.map(String::valueOf)
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.filter(path -> !path.startsWith("."))
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.sorted()
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.collect(Collectors.joining("; "));
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System.out.println("list(): " + joined);
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}
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}
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private static void testLines() throws IOException {
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try (Stream<String> stream = Files.lines(Paths.get("res/readme.txt"))) {
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stream
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.filter(line -> line.contains("print"))
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.map(String::trim)
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.forEach(System.out::println);
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}
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}
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private static void testReadWriteLines() throws IOException {
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List<String> lines = Files.readAllLines(Paths.get("res/readme.txt"));
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lines.add("print('foobar');");
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Files.write(Paths.get("res", "readme2.txt"), lines);
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}
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}

‎src/io/vakin/java8/TimeTest.java

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package io.vakin.java8;
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import java.time.Clock;
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import java.time.DayOfWeek;
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import java.time.Instant;
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import java.time.LocalDate;
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import java.time.LocalDateTime;
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import java.time.LocalTime;
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import java.time.Month;
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import java.time.ZoneId;
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import java.time.format.DateTimeFormatter;
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import java.time.format.FormatStyle;
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import java.time.temporal.ChronoField;
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import java.time.temporal.ChronoUnit;
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import java.util.Date;
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import java.util.Locale;
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public class TimeTest {
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public static void main(String[] args) {
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localDate();
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localDateTime();
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localTime();
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}
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private static void localTime() {
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Clock clock = Clock.systemDefaultZone();
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long t0 = clock.millis();
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System.out.println(t0);
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Instant instant = clock.instant();
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Date legacyDate = Date.from(instant);
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ZoneId zone1 = ZoneId.of("Europe/Berlin");
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ZoneId zone2 = ZoneId.of("Brazil/East");
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System.out.println(zone1.getRules());
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System.out.println(zone2.getRules());
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// time
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LocalTime now1 = LocalTime.now(zone1);
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LocalTime now2 = LocalTime.now(zone2);
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System.out.println(now1);
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System.out.println(now2);
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System.out.println(now1.isBefore(now2)); // false
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long hoursBetween = ChronoUnit.HOURS.between(now1, now2);
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long minutesBetween = ChronoUnit.MINUTES.between(now1, now2);
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System.out.println(hoursBetween);
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System.out.println(minutesBetween);
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// create time
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LocalTime now = LocalTime.now();
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System.out.println(now);
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LocalTime late = LocalTime.of(23, 59, 59);
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System.out.println(late);
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DateTimeFormatter germanFormatter =
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DateTimeFormatter
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.ofLocalizedTime(FormatStyle.SHORT)
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.withLocale(Locale.GERMAN);
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LocalTime leetTime = LocalTime.parse("13:37", germanFormatter);
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System.out.println(leetTime);
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}
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private static void localDateTime() {
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LocalDateTime sylvester = LocalDateTime.of(2014, Month.DECEMBER, 31, 23, 59, 59);
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DayOfWeek dayOfWeek = sylvester.getDayOfWeek();
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System.out.println(dayOfWeek); // WEDNESDAY
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Month month = sylvester.getMonth();
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System.out.println(month); // DECEMBER
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long minuteOfDay = sylvester.getLong(ChronoField.MINUTE_OF_DAY);
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System.out.println(minuteOfDay); // 1439
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Instant instant = sylvester
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.atZone(ZoneId.systemDefault())
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.toInstant();
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Date legacyDate = Date.from(instant);
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System.out.println(legacyDate); // Wed Dec 31 23:59:59 CET 2014
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DateTimeFormatter formatter =
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DateTimeFormatter
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.ofPattern("MMM dd, yyyy - HH:mm");
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LocalDateTime parsed = LocalDateTime.parse("Nov 03, 2014 - 07:13", formatter);
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String string = parsed.format(formatter);
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System.out.println(string);
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}
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private static void localDate() {
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LocalDate today = LocalDate.now();
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LocalDate tomorrow = today.plus(1, ChronoUnit.DAYS);
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LocalDate yesterday = tomorrow.minusDays(2);
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System.out.println(today);
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System.out.println(tomorrow);
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System.out.println(yesterday);
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LocalDate independenceDay = LocalDate.of(2014, Month.JULY, 4);
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DayOfWeek dayOfWeek = independenceDay.getDayOfWeek();
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System.out.println(dayOfWeek); // FRIDAY
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DateTimeFormatter germanFormatter =
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DateTimeFormatter
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.ofLocalizedDate(FormatStyle.MEDIUM)
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.withLocale(Locale.GERMAN);
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LocalDate xmas = LocalDate.parse("24.12.2014", germanFormatter);
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System.out.println(xmas); // 2014-12-24
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}
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}

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