Create new module core-java-string-operations-6

Move code for the Find the Longest Word in a String article

core-java-modules/core-java-string-operations-6/README.md

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+
+### Relevant Articles:
+
+- [Find the Longest Word in a Given String in Java](https://www.baeldung.com/java-longest-word-string)

core-java-modules/core-java-string-operations-6/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-string-operations-6</artifactId>
+    <name>core-java-string-operations-6</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+
+</project>

core-java-modules/core-java-string-operations-6/src/main/java/com/baeldung/longestword/LongestWordFinder.java

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+package com.baeldung.longestword;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+public class LongestWordFinder {
+
+    public Optional<String> findLongestWord(String sentence) {
+        return Optional.ofNullable(sentence)
+          .filter(string -> !string.trim()
+            .isEmpty())
+          .map(string -> string.split("\\s"))
+          .map(Arrays::asList)
+          .map(list -> Collections.max(list, Comparator.comparingInt(String::length)));
+    }
+
+    public List<String> findLongestWords(String sentence) {
+        if (sentence == null || sentence.trim()
+          .isEmpty()) {
+            return Collections.emptyList();
+        }
+        String[] words = sentence.split("\\s");
+        int maxWordLength = Arrays.stream(words)
+          .mapToInt(String::length)
+          .max()
+          .orElseThrow();
+        return Arrays.stream(words)
+          .filter(word -> word.length() == maxWordLength)
+          .collect(Collectors.toList());
+    }
+
+}

core-java-modules/core-java-string-operations-6/src/test/java/com/baeldung/longestword/LongestWordFinderUnitTest.java

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+package com.baeldung.longestword;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class LongestWordFinderUnitTest {
+
+    LongestWordFinder longestWordFinder = new LongestWordFinder();
+
+    @Test
+    void givenNull_whenFindLongestWord_thenEmpty() {
+        assertThat(longestWordFinder.findLongestWord(null)).isEmpty();
+    }
+
+    @Test
+    void givenEmptyString_whenFindLongestWord_thenEmpty() {
+        assertThat(longestWordFinder.findLongestWord("")).isEmpty();
+    }
+
+    @Test
+    void givenStringWithOnlySpaces_whenFindLongestWord_thenEmpty() {
+        assertThat(longestWordFinder.findLongestWord("   ")).isEmpty();
+    }
+
+    @Test
+    void givenAPhraseWithALongestWord_whenFindLongestWord_thenLongestWordOfThePhrase() {
+        assertThat(longestWordFinder.findLongestWord("This is a phrase with words")).hasValue("phrase");
+    }
+
+    @Test
+    void givenAPhraseWithVariousWordsOfMaxLength_whenFindLongestWord_thenAnyOfTheLongestsWordsOfThePhrase() {
+        assertThat(longestWordFinder.findLongestWord("Baeldung is another word of size eight in this sentence")
+          .get()).isIn("Baeldung", "sentence");
+    }
+
+    @Test
+    void givenNull_whenFindLongestWords_thenEmpty() {
+        assertThat(longestWordFinder.findLongestWords(null)).isEmpty();
+    }
+
+    @Test
+    void givenEmptyString_whenFindLongestWords_thenEmpty() {
+        assertThat(longestWordFinder.findLongestWords("")).isEmpty();
+    }
+
+    @Test
+    void givenStringWithOnlySpaces_whenFindLongestWords_thenEmpty() {
+        assertThat(longestWordFinder.findLongestWords("   ")).isEmpty();
+    }
+
+    @Test
+    void givenAPhraseWithALongestWord_whenFindLongestWords_thenLongestWordOfThePhrase() {
+        assertThat(longestWordFinder.findLongestWords("This is a phrase with words")).containsExactly("phrase");
+    }
+
+    @Test
+    void givenAPhraseWithVariousWordsOfMaxLength_whenFindLongestWords_thenAllLongestsWords() {
+        assertThat(longestWordFinder.findLongestWords("Baeldung is another word of size eight in this sentence")).containsExactly("Baeldung", "sentence");
+    }
+
+}