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alexVengrovsk
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Code for the article "Java 8’s Features"
alextrentton@gmail.com
1 parent 3896065 commit 433bc63

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‎core-java-8/src/main/java/com/baeldung/java_8_features/Address.java‎

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package com.baeldung.java_8_features;
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/**
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* Created by Alex Vengr
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*/
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public class Address {
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private String street;
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public String getStreet() {
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return street;
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}
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public void setStreet(String street) {
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this.street = street;
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}
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/CustomException.java‎

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package com.baeldung.java_8_features;
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/**
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* Created by Alex Vengr
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*/
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public class CustomException extends RuntimeException {
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/Detail.java‎

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package com.baeldung.java_8_features;
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import java.util.Arrays;
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import java.util.List;
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/**
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* Created by Alex Vengrov
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*/
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public class Detail {
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private static final List<String> PARTS = Arrays.asList("turbine", "pump");
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public List<String> getParts() {
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return PARTS;
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}
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/OptionalAddress.java‎

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package com.baeldung.java_8_features;
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import java.util.Optional;
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/**
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* Created by Alex Vengrov
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*/
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public class OptionalAddress {
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private String street;
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public Optional<String> getStreet() {
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return Optional.ofNullable(street);
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}
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public void setStreet(String street) {
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this.street = street;
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}
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/OptionalUser.java‎

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package com.baeldung.java_8_features;
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import java.util.Optional;
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/**
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* Created by Alex Vengrov
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*/
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public class OptionalUser {
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private OptionalAddress address;
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public Optional<OptionalAddress> getAddress() {
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return Optional.of(address);
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}
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public void setAddress(OptionalAddress address) {
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this.address = address;
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}
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/User.java‎

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package com.baeldung.java_8_features;
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import java.util.Optional;
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/**
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* Created by Alex Vengrov
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*/
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public class User {
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private String name;
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private Address address;
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public Address getAddress() {
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return address;
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}
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public void setAddress(Address address) {
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this.address = address;
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}
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public User() {
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}
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public User(String name) {
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this.name = name;
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}
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public static boolean isRealUser(User user) {
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return true;
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}
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public String getOrThrow() {
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String value = null;
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Optional<String> valueOpt = Optional.ofNullable(value);
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String result = valueOpt.orElseThrow(CustomException::new).toUpperCase();
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return result;
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}
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public boolean isLegalName(String name) {
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return name.length() > 3 && name.length() < 16;
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}
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/Vehicle.java‎

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package com.baeldung.java_8_features;
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/**
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* Created by Alex Vengrov
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*/
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public interface Vehicle {
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void moveTo(long altitude, long longitude);
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static String producer() {
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return "N&F Vehicles";
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}
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default long[] startPosition() {
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return new long[]{23, 15};
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}
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default String getOverview() {
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return "ATV made by " + producer();
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}
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}

‎core-java-8/src/main/java/com/baeldung/java_8_features/VehicleImpl.java‎

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package com.baeldung.java_8_features;
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/**
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* Created by 1 on 15.05.2016.
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*/
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public class VehicleImpl implements Vehicle {
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@Override
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public void moveTo(long altitude, long longitude) {
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//do nothing
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}
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}

‎core-java-8/src/test/java/com/baeldung/java8/Java8Features.java‎

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package com.baeldung.java8;
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import com.baeldung.java_8_features.*;
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import org.junit.Before;
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import org.junit.Test;
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import org.mockito.Mock;
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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.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Optional;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertFalse;
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import static org.junit.Assert.assertTrue;
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import static org.mockito.Mockito.mock;
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/**
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* Created by Alex Vengrov
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*/
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public class Java8Features {
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private List<String> list;
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@Before
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public void init() {
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list = new ArrayList<>();
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list.add("One");
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list.add("OneAndOnly");
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list.add("Derek");
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list.add("Change");
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list.add("factory");
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list.add("justBefore");
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list.add("Italy");
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list.add("Italy");
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list.add("Thursday");
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list.add("");
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list.add("");
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}
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@Test
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public void callMethods_whenExpectedResults_thenCorrect() {
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Vehicle vehicle = new VehicleImpl();
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String overview = vehicle.getOverview();
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long[] startPosition = vehicle.startPosition();
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String producer = Vehicle.producer();
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assertEquals(overview, "ATV made by N&F Vehicles");
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assertEquals(startPosition[0], 23);
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assertEquals(startPosition[1], 15);
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assertEquals(producer, "N&F Vehicles");
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}
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@Test
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public void checkStreamOperations_whenWorkAsSuppose_thenCorrect() {
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String[] arr = new String[]{"a", "b", "c"};
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Stream<String> streamArr = Arrays.stream(arr);
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Stream<String> streamOf = Stream.of("a", "b", "c");
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assertEquals(streamArr.count(), 3);
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long count = list.stream().distinct().count();
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assertEquals(count, 9);
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list.parallelStream().forEach(element -> doWork(element));
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Stream<String> streamFilter = list.stream().filter(element -> element.isEmpty());
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assertEquals(streamFilter.count(), 2);
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List<String> uris = new ArrayList<>();
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uris.add("C:\\My.txt");
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Stream<Path> streamMap = uris.stream().map(uri -> Paths.get(uri));
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assertEquals(streamMap.count(), 1);
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List<Detail> details = new ArrayList<>();
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details.add(new Detail());
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details.add(new Detail());
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Stream<String> streamFlatMap = details.stream()
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.flatMap(detail -> detail.getParts().stream());
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assertEquals(streamFlatMap.count(), 4);
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boolean isValid = list.stream().anyMatch(element -> element.contains("h"));
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boolean isValidOne = list.stream().allMatch(element -> element.contains("h"));
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boolean isValidTwo = list.stream().noneMatch(element -> element.contains("h"));
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assertTrue(isValid);
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assertFalse(isValidOne);
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assertFalse(isValidTwo);
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List<Integer> integers = new ArrayList<>();
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integers.add(1);
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integers.add(1);
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integers.add(1);
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Integer reduced = integers.stream().reduce(23, (a, b) -> a + b);
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assertTrue(reduced == 26);
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List<String> resultList = list.stream()
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.map(element -> element.toUpperCase())
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.collect(Collectors.toList());
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assertEquals(resultList.size(), list.size());
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assertTrue(resultList.contains(""));
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}
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@Test
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public void checkMethodReferences_whenWork_thenCorrect() {
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List<User> users = new ArrayList<>();
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users.add(new User());
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users.add(new User());
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boolean isReal = users.stream().anyMatch(u -> User.isRealUser(u));
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boolean isRealRef = users.stream().anyMatch(User::isRealUser);
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assertTrue(isReal);
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assertTrue(isRealRef);
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User user = new User();
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boolean isLegalName = list.stream().anyMatch(user::isLegalName);
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assertTrue(isLegalName);
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long count = list.stream().filter(String::isEmpty).count();
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assertEquals(count, 2);
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Stream<User> stream = list.stream().map(User::new);
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List<User> userList = stream.collect(Collectors.toList());
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assertEquals(userList.size(), list.size());
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assertTrue(userList.get(0) instanceof User);
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}
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@Test
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public void checkOptional_whenAsExpected_thenCorrect() {
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Optional<String> optionalEmpty = Optional.empty();
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assertFalse(optionalEmpty.isPresent());
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String str = "value";
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Optional<String> optional = Optional.of(str);
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assertEquals(optional.get(), "value");
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Optional<String> optionalNullable = Optional.ofNullable(str);
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Optional<String> optionalNull = Optional.ofNullable(null);
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assertEquals(optionalNullable.get(), "value");
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assertFalse(optionalNull.isPresent());
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List<String> listOpt = Optional.of(list).orElse(new ArrayList<>());
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List<String> listNull = null;
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List<String> listOptNull = Optional.ofNullable(listNull).orElse(new ArrayList<>());
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assertTrue(listOpt == list);
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assertTrue(listOptNull.isEmpty());
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Optional<User> user = Optional.ofNullable(getUser());
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String result = user.map(User::getAddress)
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.map(Address::getStreet)
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.orElse("not specified");
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assertEquals(result, "1st Avenue");
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Optional<OptionalUser> optionalUser = Optional.ofNullable(getOptionalUser());
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String resultOpt = optionalUser.flatMap(OptionalUser::getAddress)
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.flatMap(OptionalAddress::getStreet)
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.orElse("not specified");
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assertEquals(resultOpt, "1st Avenue");
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Optional<User> userNull = Optional.ofNullable(getUserNull());
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String resultNull = userNull.map(User::getAddress)
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.map(Address::getStreet)
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.orElse("not specified");
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assertEquals(resultNull, "not specified");
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Optional<OptionalUser> optionalUserNull = Optional.ofNullable(getOptionalUserNull());
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String resultOptNull = optionalUserNull.flatMap(OptionalUser::getAddress)
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.flatMap(OptionalAddress::getStreet)
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.orElse("not specified");
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assertEquals(resultOptNull, "not specified");
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}
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@Test(expected = CustomException.class)
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public void callMethod_whenCustomException_thenCorrect() {
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User user = new User();
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String result = user.getOrThrow();
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}
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private User getUser() {
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User user = new User();
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Address address = new Address();
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address.setStreet("1st Avenue");
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user.setAddress(address);
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return user;
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}
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private OptionalUser getOptionalUser() {
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OptionalUser user = new OptionalUser();
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OptionalAddress address = new OptionalAddress();
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address.setStreet("1st Avenue");
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user.setAddress(address);
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return user;
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}
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private OptionalUser getOptionalUserNull() {
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OptionalUser user = new OptionalUser();
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OptionalAddress address = new OptionalAddress();
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address.setStreet(null);
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user.setAddress(address);
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return user;
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}
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private User getUserNull() {
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User user = new User();
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Address address = new Address();
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address.setStreet(null);
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user.setAddress(address);
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return user;
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}
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private void doWork(String string) {
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//just imitate an amount of work
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}
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}

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