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BAEL-5754 Convert a List of String to a comma-separated String (#12737) 

* BAEL-5617 Handle classes with the same name in Java

code samples

* BAEL-5617 Handle classes with the same name in Java

update project module

* BAEL-5754 Convert a List of String to a comma-separated String

code samples

* BAEL-5754 update unit test class name

* BAEL-5754 update unit test methods naming

* BAEL-5754 update tests order so to reflect the article
This commit is contained in:
Bogdan Cardoş 2022-09-30 07:38:08 +03:00 committed by GitHub
parent abc3e0235e
commit e8168990c5
2 changed files with 139 additions and 0 deletions
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7
core-java-modules/core-java-collections-list-4/pom.xml
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@ -56,6 +56,12 @@
<version>${assertj.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
@ -80,6 +86,7 @@
<assertj.version>3.22.0</assertj.version>
<maven.compiler.source.version>17</maven.compiler.source.version>
<maven.compiler.target.version>17</maven.compiler.target.version>
<spring.version>5.3.22</spring.version>
</properties>
</project>

132
core-java-modules/core-java-collections-list-4/src/test/java/com/baeldung/list/tostring/ListToStringUnitTest.java Normal file
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@ -0,0 +1,132 @@
package com.baeldung.list.tostring;
import static org.assertj.core.api.Assertions.assertThat;
import java.util.Arrays;
import java.util.List;
import java.util.StringJoiner;
import java.util.stream.Collectors;
import org.junit.jupiter.api.Test;
class ListToStringUnitTest {
@Test
void givenAListOfString_whenUsingJava8_thenConvertToStringByUsingString() {
List<String> arraysAsList = Arrays.asList("ONE", "TWO", "THREE");
String commaSeparatedString = String.join(",", arraysAsList);
assertThat(commaSeparatedString).isEqualTo("ONE,TWO,THREE");
}
@Test
void givenAListOfString_whenUsingJava8_thenConvertToStringByUsingStringJoiner() {
List<String> arraysAsList = Arrays.asList("ONE", "TWO", "THREE");
StringJoiner stringJoiner = new StringJoiner(",");
arraysAsList.stream()
.forEach(v -> stringJoiner.add(v));
String commaSeparatedString = stringJoiner.toString();
assertThat(commaSeparatedString).isEqualTo("ONE,TWO,THREE");
StringJoiner stringJoinerWithDelimiterPrefixSuffix = new StringJoiner(",", "[", "]");
arraysAsList.stream()
.forEach(v -> stringJoinerWithDelimiterPrefixSuffix.add(v));
String commaSeparatedStringWithDelimiterPrefixSuffix = stringJoinerWithDelimiterPrefixSuffix.toString();
assertThat(commaSeparatedStringWithDelimiterPrefixSuffix).isEqualTo("[ONE,TWO,THREE]");
}
@Test
void givenAListOfString_whenUsingJava8_thenConvertToStringByUsingCollectors() {
List<String> arraysAsList = Arrays.asList("ONE", "TWO", "THREE");
String commaSeparatedUsingCollect = arraysAsList.stream()
.collect(Collectors.joining(","));
assertThat(commaSeparatedUsingCollect).isEqualTo("ONE,TWO,THREE");
String commaSeparatedObjectToString = arraysAsList.stream()
.map(Object::toString)
.collect(Collectors.joining(","));
assertThat(commaSeparatedObjectToString).isEqualTo("ONE,TWO,THREE");
String commaSeparatedStringValueOf = arraysAsList.stream()
.map(String::valueOf)
.collect(Collectors.joining(","));
assertThat(commaSeparatedStringValueOf).isEqualTo("ONE,TWO,THREE");
String commaSeparatedStringValueOfWithDelimiterPrefixSuffix = arraysAsList.stream()
.map(String::valueOf)
.collect(Collectors.joining(",", "[", "]"));
assertThat(commaSeparatedStringValueOfWithDelimiterPrefixSuffix).isEqualTo("[ONE,TWO,THREE]");
String commaSeparatedUsingReduce = arraysAsList.stream()
.reduce((x, y) -> x + "," + y)
.get();
assertThat(commaSeparatedUsingReduce).isEqualTo("ONE,TWO,THREE");
}
@Test
void givenAListOfString_whenUsingApacheCommonsLang_thenConvertToStringByUsingStringUtils() {
List<String> arraysAsList = Arrays.asList("ONE", "TWO", "THREE");
String commaSeparatedString = org.apache.commons.lang3.StringUtils.join(arraysAsList, ",");
assertThat(commaSeparatedString).isEqualTo("ONE,TWO,THREE");
String commaSeparatedStringIndex = org.apache.commons.lang3.StringUtils.join(arraysAsList.toArray(), ",", 0, 3);
assertThat(commaSeparatedStringIndex).isEqualTo("ONE,TWO,THREE");
}
@Test
void givenAListOfString_whenUsingSpringCore_thenConvertToStringByUsingStringUtils() {
List<String> arraysAsList = Arrays.asList("ONE", "TWO", "THREE");
String collectionToCommaDelimitedString = org.springframework.util.StringUtils.collectionToCommaDelimitedString(arraysAsList);
assertThat(collectionToCommaDelimitedString).isEqualTo("ONE,TWO,THREE");
String collectionToDelimitedString = org.springframework.util.StringUtils.collectionToDelimitedString(arraysAsList, ",");
assertThat(collectionToDelimitedString).isEqualTo("ONE,TWO,THREE");
}
@Test
void givenAListOfString_whenUsingGoogleGuava_thenConvertToStringByUsingJoiner() {
List<String> arraysAsList = Arrays.asList("ONE", "TWO", "THREE");
String commaSeparatedString = com.google.common.base.Joiner.on(",")
.join(arraysAsList);
assertThat(commaSeparatedString).isEqualTo("ONE,TWO,THREE");
List<String> arraysAsListWithNull = Arrays.asList("ONE", null, "TWO", null, "THREE");
String commaSeparatedStringSkipNulls = com.google.common.base.Joiner.on(",")
.skipNulls()
.join(arraysAsListWithNull);
assertThat(commaSeparatedStringSkipNulls).isEqualTo("ONE,TWO,THREE");
String commaSeparatedStringUseForNull = com.google.common.base.Joiner.on(",")
.useForNull(" ")
.join(arraysAsListWithNull);
assertThat(commaSeparatedStringUseForNull).isEqualTo("ONE, ,TWO, ,THREE");
}
}