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[BAEL-16531] - Move all the existing articles on "optional" under java-optional

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This commit is contained in:
catalin-burcea
2019-11-26 12:01:07 +02:00
parent 5df99fa226
commit 34e61efb0a
29 changed files with 230 additions and 201 deletions
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26
core-java-modules/core-java-9/src/main/java/com/baeldung/optionals/Optionals.java
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@@ -1,26 +0,0 @@
package com.baeldung.optionals;
import java.util.Optional;
public class Optionals {
public static <T> Optional<T> or(Optional<T> optional, Optional<T> fallback) {
return optional.isPresent() ? optional : fallback;
}
public static Optional<String> getName(Optional<String> name) {
return name.or(() -> getCustomMessage());
}
public static com.google.common.base.Optional<String> getOptionalGuavaName(com.google.common.base.Optional<String> name) {
return name.or(getCustomMessageGuava());
}
private static Optional<String> getCustomMessage() {
return Optional.of("Name not provided");
}
private static com.google.common.base.Optional<String> getCustomMessageGuava() {
return com.google.common.base.Optional.of("Name not provided");
}
}

61
core-java-modules/core-java-9/src/test/java/com/baeldung/java9/Java9OptionalsStreamUnitTest.java
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@@ -1,61 +0,0 @@
package com.baeldung.java9;
import static org.junit.Assert.assertEquals;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.junit.Test;
public class Java9OptionalsStreamUnitTest {
private static List<Optional<String>> listOfOptionals = Arrays.asList(Optional.empty(), Optional.of("foo"), Optional.empty(), Optional.of("bar"));
@Test
public void filterOutPresentOptionalsWithFilter() {
assertEquals(4, listOfOptionals.size());
List<String> filteredList = listOfOptionals.stream().filter(Optional::isPresent).map(Optional::get).collect(Collectors.toList());
assertEquals(2, filteredList.size());
assertEquals("foo", filteredList.get(0));
assertEquals("bar", filteredList.get(1));
}
@Test
public void filterOutPresentOptionalsWithFlatMap() {
assertEquals(4, listOfOptionals.size());
List<String> filteredList = listOfOptionals.stream().flatMap(o -> o.isPresent() ? Stream.of(o.get()) : Stream.empty()).collect(Collectors.toList());
assertEquals(2, filteredList.size());
assertEquals("foo", filteredList.get(0));
assertEquals("bar", filteredList.get(1));
}
@Test
public void filterOutPresentOptionalsWithFlatMap2() {
assertEquals(4, listOfOptionals.size());
List<String> filteredList = listOfOptionals.stream().flatMap(o -> o.map(Stream::of).orElseGet(Stream::empty)).collect(Collectors.toList());
assertEquals(2, filteredList.size());
assertEquals("foo", filteredList.get(0));
assertEquals("bar", filteredList.get(1));
}
@Test
public void filterOutPresentOptionalsWithJava9() {
assertEquals(4, listOfOptionals.size());
List<String> filteredList = listOfOptionals.stream().flatMap(Optional::stream).collect(Collectors.toList());
assertEquals(2, filteredList.size());
assertEquals("foo", filteredList.get(0));
assertEquals("bar", filteredList.get(1));
}
}

51
core-java-modules/core-java-9/src/test/java/com/baeldung/optionals/OptionalsTest.java
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@@ -1,51 +0,0 @@
package com.baeldung.optionals;
import static org.junit.Assert.assertEquals;
import java.util.Optional;
import org.junit.Test;
public class OptionalsTest {
@Test
public void givenOptional_whenEmptyValue_thenCustomMessage() {
assertEquals(Optional.of("Name not provided"), Optionals.getName(Optional.ofNullable(null)));
}
@Test
public void givenOptional_whenValue_thenOptional() {
String name = "Filan Fisteku";
Optional<String> optionalString = Optional.ofNullable(name);
assertEquals(optionalString, Optionals.getName(optionalString));
}
@Test
public void givenOptional_whenValue_thenOptionalGeneralMethod() {
String name = "Filan Fisteku";
String missingOptional = "Name not provided";
Optional<String> optionalString = Optional.ofNullable(name);
Optional<String> fallbackOptionalString = Optional.ofNullable(missingOptional);
assertEquals(optionalString, Optionals.or(optionalString, fallbackOptionalString));
}
@Test
public void givenEmptyOptional_whenValue_thenOptionalGeneralMethod() {
String missingOptional = "Name not provided";
Optional<String> optionalString = Optional.empty();
Optional<String> fallbackOptionalString = Optional.ofNullable(missingOptional);
assertEquals(fallbackOptionalString, Optionals.or(optionalString, fallbackOptionalString));
}
@Test
public void givenGuavaOptional_whenInvoke_thenOptional() {
String name = "Filan Fisteku";
com.google.common.base.Optional<String> stringOptional = com.google.common.base.Optional.of(name);
assertEquals(stringOptional, Optionals.getOptionalGuavaName(stringOptional));
}
@Test
public void givenGuavaOptional_whenNull_thenDefaultText() {
assertEquals(com.google.common.base.Optional.of("Name not provided"), Optionals.getOptionalGuavaName(com.google.common.base.Optional.fromNullable(null)));
}
}