Move articles out of java-strings part1

core-java-modules/core-java-string-conversions/README.md

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+## Java String Conversions
+
+This module contains articles about string conversions from/to another type.
+
+### Relevant Articles:
+- [Converting String to Stream of chars](https://www.baeldung.com/java-string-to-stream)
+- [Converting Strings to Enums in Java](https://www.baeldung.com/java-string-to-enum)
+- [Convert a String to Title Case](https://www.baeldung.com/java-string-title-case)
+- [Convert java.util.Date to String](https://www.baeldung.com/java-util-date-to-string)
+- [Converting a Stack Trace to a String in Java](https://www.baeldung.com/java-stacktrace-to-string)
+- [Image to Base64 String Conversion](https://www.baeldung.com/java-base64-image-string)
+- [Convert a Comma Separated String to a List in Java](https://www.baeldung.com/java-string-with-separator-to-list)
+- [Converting Java String to Double](https://www.baeldung.com/java-string-to-double)
+- [Convert Char to String in Java](https://www.baeldung.com/java-convert-char-to-string)
+- [Convert String to int or Integer in Java](https://www.baeldung.com/java-convert-string-to-int-or-integer)
+- More articles: [[next -->]](/core-java-string-conversions-2)
+"Counting Words in a String

core-java-modules/core-java-string-conversions/pom.xml

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+<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-conversions</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>core-java-string-conversions</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.ibm.icu</groupId>
+            <artifactId>icu4j</artifactId>
+            <version>${icu4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-library</artifactId>
+            <version>${org.hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-string-conversions</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+    <properties>
+        <icu4j.version>61.1</icu4j.version>
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+
+</project>

core-java-modules/core-java-string-conversions/src/main/java/com/baeldung/stringtoenum/PizzaStatusEnum.java

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+package com.baeldung.stringtoenum;
+
+public enum PizzaStatusEnum {
+    ORDERED(5) {
+        @Override
+        public boolean isOrdered() {
+            return true;
+        }
+    },
+    READY(2) {
+        @Override
+        public boolean isReady() {
+            return true;
+        }
+    },
+    DELIVERED(0) {
+        @Override
+        public boolean isDelivered() {
+            return true;
+        }
+    };
+
+    private int timeToDelivery;
+
+    public boolean isOrdered() {
+        return false;
+    }
+
+    public boolean isReady() {
+        return false;
+    }
+
+    public boolean isDelivered() {
+        return false;
+    }
+
+    public int getTimeToDelivery() {
+        return timeToDelivery;
+    }
+
+    PizzaStatusEnum(int timeToDelivery) {
+        this.timeToDelivery = timeToDelivery;
+    }
+}

core-java-modules/core-java-string-conversions/src/main/java/com/baeldung/titlecase/TitleCaseConverter.java

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+package com.baeldung.titlecase;
+
+import com.ibm.icu.lang.UCharacter;
+import com.ibm.icu.text.BreakIterator;
+import org.apache.commons.lang3.text.WordUtils;
+
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+public class TitleCaseConverter {
+
+    private static final String WORD_SEPARATOR = " ";
+
+    public static String convertToTitleCaseIteratingChars(String text) {
+        if (text == null || text.isEmpty()) {
+            return text;
+        }
+
+        StringBuilder converted = new StringBuilder();
+
+        boolean convertNext = true;
+        for (char ch : text.toCharArray()) {
+            if (Character.isSpaceChar(ch)) {
+                convertNext = true;
+            } else if (convertNext) {
+                ch = Character.toTitleCase(ch);
+                convertNext = false;
+            } else {
+                ch = Character.toLowerCase(ch);
+            }
+            converted.append(ch);
+        }
+
+        return converted.toString();
+    }
+
+    public static String convertToTitleCaseSplitting(String text) {
+        if (text == null || text.isEmpty()) {
+            return text;
+        }
+
+        return Arrays
+          .stream(text.split(WORD_SEPARATOR))
+          .map(word -> word.isEmpty()
+            ? word
+            : Character.toTitleCase(word.charAt(0)) + word
+              .substring(1)
+              .toLowerCase())
+          .collect(Collectors.joining(WORD_SEPARATOR));
+    }
+
+    public static String convertToTitleCaseIcu4j(String text) {
+        if (text == null || text.isEmpty()) {
+            return text;
+        }
+
+        return UCharacter.toTitleCase(text, BreakIterator.getTitleInstance());
+    }
+
+    public static String convertToTileCaseWordUtilsFull(String text) {
+        return WordUtils.capitalizeFully(text);
+    }
+
+    public static String convertToTileCaseWordUtils(String text) {
+        return WordUtils.capitalize(text);
+    }
+
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/chartostring/CharToStringUnitTest.java

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+package com.baeldung.chartostring;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class CharToStringUnitTest {
+
+    @Test
+    public void givenChar_whenCallingStringValueOf_shouldConvertToString() {
+        final char givenChar = 'x';
+
+        final String result = String.valueOf(givenChar);
+
+        assertThat(result).isEqualTo("x");
+    }
+
+    @Test
+    public void givenChar_whenCallingToStringOnCharacter_shouldConvertToString() {
+        final char givenChar = 'x';
+
+        final String result = Character.toString(givenChar);
+
+        assertThat(result).isEqualTo("x");
+    }
+
+    @Test
+    public void givenChar_whenCallingCharacterConstructor_shouldConvertToString3() {
+        final char givenChar = 'x';
+
+        final String result = new Character(givenChar).toString();
+
+        assertThat(result).isEqualTo("x");
+    }
+
+    @Test
+    public void givenChar_whenConcatenated_shouldConvertToString4() {
+        final char givenChar = 'x';
+
+        final String result = givenChar + "";
+
+        assertThat(result).isEqualTo("x");
+    }
+
+    @Test
+    public void givenChar_whenFormated_shouldConvertToString5() {
+        final char givenChar = 'x';
+
+        final String result = String.format("%c", givenChar);
+
+        assertThat(result).isEqualTo("x");
+    }
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/datetostring/DateToStringFormatterUnitTest.java

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+package com.baeldung.datetostring;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+
+import static org.junit.Assert.assertEquals;
+
+public class DateToStringFormatterUnitTest {
+
+    private static final String DATE_FORMAT = "MMM d, yyyy HH:mm a";
+    private static final String EXPECTED_STRING_DATE = "Aug 1, 2018 12:00 PM";
+    private static Date date;
+
+    @BeforeClass
+    public static void setUp() {
+        TimeZone.setDefault(TimeZone.getTimeZone("CET"));
+        Calendar calendar = Calendar.getInstance();
+        calendar.set(2018, Calendar.AUGUST, 1, 12, 0);
+        date = calendar.getTime();
+    }
+
+    @Test
+    public void whenDateConvertedUsingSimpleDateFormatToString_thenCorrect() {
+        DateFormat formatter = new SimpleDateFormat(DATE_FORMAT);
+        String formattedDate = formatter.format(date);
+
+        assertEquals(EXPECTED_STRING_DATE, formattedDate);
+    }
+
+    @Test
+    public void whenDateConvertedUsingDateFormatToString_thenCorrect() {
+        String formattedDate = DateFormat
+          .getDateTimeInstance(DateFormat.MEDIUM, DateFormat.SHORT, Locale.US)
+          .format(date);
+
+        assertEquals(EXPECTED_STRING_DATE, formattedDate);
+    }
+
+    @Test
+    public void whenDateConvertedUsingFormatterToString_thenCorrect() {
+        String formattedDate = String.format("%1$tb %1$te, %1$tY %1$tI:%1$tM %1$Tp", date);
+
+        assertEquals(EXPECTED_STRING_DATE, formattedDate);
+    }
+
+    @Test
+    public void whenDateConvertedUsingDateTimeApiToString_thenCorrect() {
+        DateTimeFormatter fmt = DateTimeFormatter.ofPattern(DATE_FORMAT);
+        Instant instant = date.toInstant();
+        LocalDateTime ldt = instant
+          .atZone(ZoneId.of("CET"))
+          .toLocalDateTime();
+        String formattedDate = ldt.format(fmt);
+
+        assertEquals(EXPECTED_STRING_DATE, formattedDate);
+    }
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/filetobase64conversion/FileToBase64StringConversionUnitTest.java

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+package com.baeldung.filetobase64conversion;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Base64;
+
+import static org.junit.Assert.assertTrue;
+
+public class FileToBase64StringConversionUnitTest {
+
+    private String inputFilePath = "test_image.jpg";
+    private String outputFilePath = "test_image_copy.jpg";
+
+    @Test
+    public void fileToBase64StringConversion() throws IOException {
+        //load file from /src/test/resources
+        ClassLoader classLoader = getClass().getClassLoader();
+        File inputFile = new File(classLoader
+          .getResource(inputFilePath)
+          .getFile());
+
+        byte[] fileContent = FileUtils.readFileToByteArray(inputFile);
+        String encodedString = Base64
+          .getEncoder()
+          .encodeToString(fileContent);
+
+        //create output file
+        File outputFile = new File(inputFile
+          .getParentFile()
+          .getAbsolutePath() + File.pathSeparator + outputFilePath);
+
+        // decode the string and write to file
+        byte[] decodedBytes = Base64
+          .getDecoder()
+          .decode(encodedString);
+        FileUtils.writeByteArrayToFile(outputFile, decodedBytes);
+
+        assertTrue(FileUtils.contentEquals(inputFile, outputFile));
+    }
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/stringtodouble/StringToDoubleConversionUnitTest.java

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+package com.baeldung.stringtodouble;
+
+import static org.junit.Assert.assertEquals;
+
+import java.text.DecimalFormat;
+import java.text.ParseException;
+
+import org.junit.Test;
+
+public class StringToDoubleConversionUnitTest {
+
+    @Test
+    public void givenValidString_WhenParseDouble_ThenResultIsPrimitiveDouble() {
+        assertEquals(1.23, Double.parseDouble("1.23"), 0.000001);
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_WhenParseDouble_ThenNullPointerExceptionIsThrown() {
+        Double.parseDouble(null);
+    }
+    
+    @Test(expected = NumberFormatException.class)
+    public void givenInalidString_WhenParseDouble_ThenNumberFormatExceptionIsThrown() {
+        Double.parseDouble("&");
+    }
+    
+    @Test
+    public void givenValidString_WhenValueOf_ThenResultIsPrimitiveDouble() {
+        assertEquals(1.23, Double.valueOf("1.23"), 0.000001);
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_WhenValueOf_ThenNullPointerExceptionIsThrown() {
+        Double.valueOf(null);
+    }
+    
+    @Test(expected = NumberFormatException.class)
+    public void givenInalidString_WhenValueOf_ThenNumberFormatExceptionIsThrown() {
+        Double.valueOf("&");
+    }
+    
+    @Test
+    public void givenValidString_WhenDecimalFormat_ThenResultIsValidDouble() throws ParseException {
+        assertEquals(1.23, new DecimalFormat("#").parse("1.23").doubleValue(), 0.000001);
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_WhenDecimalFormat_ThenNullPointerExceptionIsThrown() throws ParseException {
+        new DecimalFormat("#").parse(null);
+    }
+    
+    @Test(expected = ParseException.class)
+    public void givenInvalidString_WhenDecimalFormat_ThenParseExceptionIsThrown() throws ParseException {
+        new DecimalFormat("#").parse("&");
+    }
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/stringtoenum/StringToEnumUnitTest.java

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+package com.baeldung.stringtoenum;
+
+import static junit.framework.TestCase.assertTrue;
+
+import org.junit.Test;
+
+public class StringToEnumUnitTest {
+    
+    @Test
+    public void whenConvertedIntoEnum_thenGetsConvertedCorrectly() {
+        String pizzaEnumValue = "READY";
+        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
+        assertTrue(pizzaStatusEnum == PizzaStatusEnum.READY);
+    }
+    
+    @Test(expected = IllegalArgumentException.class)
+    public void whenConvertedIntoEnum_thenThrowsException() {
+        String pizzaEnumValue = "rEAdY";
+        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void givenInvalidEnumValueContentWiseAsString_whenConvertedIntoEnum_thenThrowsException() {
+        String pizzaEnumValue = "invalid";
+        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
+    }
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/stringtoint/StringToIntOrIntegerUnitTest.java

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+package com.baeldung.stringtoint;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+import com.google.common.primitives.Ints;
+
+public class StringToIntOrIntegerUnitTest {
+
+    @Test
+    public void givenString_whenParsingInt_shouldConvertToInt() {
+        String givenString = "42";
+
+        int result = Integer.parseInt(givenString);
+
+        assertThat(result).isEqualTo(42);
+    }
+
+    @Test
+    public void givenString_whenCallingIntegerValueOf_shouldConvertToInt() {
+        String givenString = "42";
+
+        Integer result = Integer.valueOf(givenString);
+
+        assertThat(result).isEqualTo(new Integer(42));
+    }
+
+    @Test
+    public void givenString_whenCallingIntegerConstructor_shouldConvertToInt() {
+        String givenString = "42";
+
+        Integer result = new Integer(givenString);
+
+        assertThat(result).isEqualTo(new Integer(42));
+    }
+
+    @Test
+    public void givenString_whenCallingIntegerDecode_shouldConvertToInt() {
+        String givenString = "42";
+
+        int result = Integer.decode(givenString);
+
+        assertThat(result).isEqualTo(42);
+    }
+
+    @Test
+    public void givenString_whenTryParse_shouldConvertToInt() {
+        String givenString = "42";
+
+        Integer result = Ints.tryParse(givenString);
+
+        assertThat(result).isEqualTo(42);
+    }
+
+    @Test(expected = NumberFormatException.class)
+    public void givenInvalidInput_whenParsingInt_shouldThrow() {
+        String givenString = "nan";
+        Integer.parseInt(givenString);
+    }
+
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/stringtolist/ConvertStringToListUnitTest.java

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+package com.baeldung.stringtolist;
+
+import com.google.common.base.Function;
+import com.google.common.base.Splitter;
+import com.google.common.collect.Lists;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
+
+public class ConvertStringToListUnitTest {
+
+    private final String countries = "Russia,Germany,England,France,Italy";
+    private final String ranks = "1,2,3,4,5, 6,7";
+    private final String emptyStrings = ",,,,,";
+    private final List<String> expectedCountriesList = Arrays.asList("Russia", "Germany", "England", "France", "Italy");
+    private final List<Integer> expectedRanksList = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
+    private final List<String> expectedEmptyStringsList = Arrays.asList("", "", "", "", "", "");
+
+    @Test
+    public void givenString_thenGetListOfStringByJava() {
+        List<String> convertedCountriesList = Arrays.asList(countries.split(",", -1));
+
+        assertEquals(expectedCountriesList, convertedCountriesList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfStringByApache() {
+        List<String> convertedCountriesList = Arrays.asList(StringUtils.splitPreserveAllTokens(countries, ","));
+
+        assertEquals(expectedCountriesList, convertedCountriesList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfStringByGuava() {
+        List<String> convertedCountriesList = Splitter.on(",")
+            .trimResults()
+            .splitToList(countries);
+
+        assertEquals(expectedCountriesList, convertedCountriesList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfStringByJava8() {
+        List<String> convertedCountriesList = Stream.of(countries.split(",", -1))
+            .collect(Collectors.toList());
+
+        assertEquals(expectedCountriesList, convertedCountriesList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfIntegerByJava() {
+        String[] convertedRankArray = ranks.split(",");
+        List<Integer> convertedRankList = new ArrayList<Integer>();
+        for (String number : convertedRankArray) {
+            convertedRankList.add(Integer.parseInt(number.trim()));
+        }
+
+        assertEquals(expectedRanksList, convertedRankList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfIntegerByGuava() {
+        List<Integer> convertedRankList = Lists.transform(Splitter.on(",")
+            .trimResults()
+            .splitToList(ranks), new Function<String, Integer>() {
+                @Override
+                public Integer apply(String input) {
+                    return Integer.parseInt(input.trim());
+                }
+            });
+
+        assertEquals(expectedRanksList, convertedRankList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfIntegerByJava8() {
+        List<Integer> convertedRankList = Stream.of(ranks.split(","))
+            .map(String::trim)
+            .map(Integer::parseInt)
+            .collect(Collectors.toList());
+
+        assertEquals(expectedRanksList, convertedRankList);
+    }
+
+    @Test
+    public void givenString_thenGetListOfIntegerByApache() {
+        String[] convertedRankArray = StringUtils.split(ranks, ",");
+        List<Integer> convertedRankList = new ArrayList<Integer>();
+        for (String number : convertedRankArray) {
+            convertedRankList.add(Integer.parseInt(number.trim()));
+        }
+
+        assertEquals(expectedRanksList, convertedRankList);
+    }
+
+    @Test
+    public void givenEmptyStrings_thenGetListOfStringByJava() {
+        List<String> convertedEmptyStringsList = Arrays.asList(emptyStrings.split(",", -1));
+
+        assertEquals(expectedEmptyStringsList, convertedEmptyStringsList);
+    }
+
+    @Test
+    public void givenEmptyStrings_thenGetListOfStringByApache() {
+        List<String> convertedEmptyStringsList = Arrays.asList(StringUtils.splitPreserveAllTokens(emptyStrings, ","));
+
+        assertEquals(expectedEmptyStringsList, convertedEmptyStringsList);
+    }
+
+    @Test
+    public void givenEmptyStrings_thenGetListOfStringByGuava() {
+        List<String> convertedEmptyStringsList = Splitter.on(",")
+            .trimResults()
+            .splitToList(emptyStrings);
+
+        assertEquals(expectedEmptyStringsList, convertedEmptyStringsList);
+    }
+
+    @Test
+    public void givenEmptyStrings_thenGetListOfStringByJava8() {
+        List<String> convertedEmptyStringsList = Stream.of(emptyStrings.split(",", -1))
+            .collect(Collectors.toList());
+
+        assertEquals(expectedEmptyStringsList, convertedEmptyStringsList);
+    }
+
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/stringtostream/StringToCharStreamUnitTest.java

@@ -0,0 +1,59 @@
+package com.baeldung.stringtostream;
+
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+
+public class StringToCharStreamUnitTest {
+
+    private String testString = "Tests";
+
+    @Test
+    public void givenTestString_whenChars_thenReturnIntStream() {
+        assertThat(testString.chars(), instanceOf(IntStream.class));
+    }
+
+    @Test
+    public void givenTestString_whenCodePoints_thenReturnIntStream() {
+        assertThat(testString.codePoints(), instanceOf(IntStream.class));
+    }
+
+    @Test
+    public void givenTestString_whenCodePoints_thenShowOccurences() throws Exception {
+        Map<Character, Integer> map = testString.codePoints()
+          .mapToObj(c -> (char) c)
+          .filter(Character::isLetter)
+          .collect(Collectors.toMap(c -> c, c -> 1, Integer::sum));
+
+        System.out.println(map);
+    }
+
+    @Test
+    public void givenIntStream_whenMapToObj_thenReturnCharacterStream() {
+        Stream<Character> characterStream = testString.chars()
+          .mapToObj(c -> (char) c);
+        Stream<Character> characterStream1 = testString.codePoints()
+          .mapToObj(c -> (char) c);
+        assertNotNull("IntStream returned by chars() did not map to Stream<Character>", characterStream);
+        assertNotNull("IntStream returned by codePoints() did not map to Stream<Character>", characterStream1);
+    }
+
+    @Test
+    public void givenIntStream_whenMapToObj_thenReturnStringStream() {
+        List<String> strings = testString.codePoints()
+          .mapToObj(c -> String.valueOf((char) c))
+          .collect(Collectors.toList());
+
+        assertEquals(strings.size(), 5);
+    }
+
+}

core-java-modules/core-java-string-conversions/src/test/java/com/baeldung/titlecase/TitleCaseConverterUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.titlecase;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class TitleCaseConverterUnitTest {
+
+    private static final String TEXT = "tHis IS a tiTLe";
+    private static final String TEXT_EXPECTED = "This Is A Title";
+    private static final String TEXT_EXPECTED_NOT_FULL = "THis IS A TiTLe";
+
+    private static final String TEXT_OTHER_DELIMITERS = "tHis, IS a   tiTLe";
+    private static final String TEXT_EXPECTED_OTHER_DELIMITERS = "This, Is A   Title";
+    private static final String TEXT_EXPECTED_OTHER_DELIMITERS_NOT_FULL = "THis, IS A   TiTLe";
+
+    @Test
+    public void whenConvertingToTitleCaseIterating_thenStringConverted() {
+        assertEquals(TEXT_EXPECTED, TitleCaseConverter.convertToTitleCaseIteratingChars(TEXT));
+    }
+
+    @Test
+    public void whenConvertingToTitleCaseSplitting_thenStringConverted() {
+        assertEquals(TEXT_EXPECTED, TitleCaseConverter.convertToTitleCaseSplitting(TEXT));
+    }
+
+    @Test
+    public void whenConvertingToTitleCaseUsingWordUtilsFull_thenStringConverted() {
+        assertEquals(TEXT_EXPECTED, TitleCaseConverter.convertToTileCaseWordUtilsFull(TEXT));
+    }
+
+    @Test
+    public void whenConvertingToTitleCaseUsingWordUtils_thenStringConvertedOnlyFirstCharacter() {
+        assertEquals(TEXT_EXPECTED_NOT_FULL, TitleCaseConverter.convertToTileCaseWordUtils(TEXT));
+    }
+
+    @Test
+    public void whenConvertingToTitleCaseUsingIcu4j_thenStringConverted() {
+        assertEquals(TEXT_EXPECTED, TitleCaseConverter.convertToTitleCaseIcu4j(TEXT));
+    }
+
+    @Test
+    public void whenConvertingToTitleCaseWithDifferentDelimiters_thenDelimitersKept() {
+        assertEquals(TEXT_EXPECTED_OTHER_DELIMITERS, TitleCaseConverter.convertToTitleCaseIteratingChars(TEXT_OTHER_DELIMITERS));
+        assertEquals(TEXT_EXPECTED_OTHER_DELIMITERS, TitleCaseConverter.convertToTitleCaseSplitting(TEXT_OTHER_DELIMITERS));
+        assertEquals(TEXT_EXPECTED_OTHER_DELIMITERS, TitleCaseConverter.convertToTileCaseWordUtilsFull(TEXT_OTHER_DELIMITERS));
+        assertEquals(TEXT_EXPECTED_OTHER_DELIMITERS_NOT_FULL, TitleCaseConverter.convertToTileCaseWordUtils(TEXT_OTHER_DELIMITERS));
+        assertEquals(TEXT_EXPECTED_OTHER_DELIMITERS, TitleCaseConverter.convertToTitleCaseIcu4j(TEXT_OTHER_DELIMITERS));
+    }
+
+    @Test
+    public void givenNull_whenConvertingToTileCase_thenReturnNull() {
+        assertEquals(null, TitleCaseConverter.convertToTitleCaseIteratingChars(null));
+        assertEquals(null, TitleCaseConverter.convertToTitleCaseSplitting(null));
+        assertEquals(null, TitleCaseConverter.convertToTileCaseWordUtilsFull(null));
+        assertEquals(null, TitleCaseConverter.convertToTileCaseWordUtils(null));
+        assertEquals(null, TitleCaseConverter.convertToTitleCaseIcu4j(null));
+    }
+
+    @Test
+    public void givenEmptyString_whenConvertingToTileCase_thenReturnEmptyString() {
+        assertEquals("", TitleCaseConverter.convertToTitleCaseIteratingChars(""));
+        assertEquals("", TitleCaseConverter.convertToTitleCaseSplitting(""));
+        assertEquals("", TitleCaseConverter.convertToTileCaseWordUtilsFull(""));
+        assertEquals("", TitleCaseConverter.convertToTileCaseWordUtils(""));
+        assertEquals("", TitleCaseConverter.convertToTitleCaseIcu4j(""));
+    }
+
+}