diff --git a/core-java-modules/core-java-collections-list-4/pom.xml b/core-java-modules/core-java-collections-list-4/pom.xml index 773f8c105b..49b3f849d4 100644 --- a/core-java-modules/core-java-collections-list-4/pom.xml +++ b/core-java-modules/core-java-collections-list-4/pom.xml @@ -56,6 +56,12 @@ ${assertj.version} test + + org.springframework + spring-core + ${spring.version} + test + @@ -80,6 +86,7 @@ 3.22.0 17 17 + 5.3.22 \ No newline at end of file diff --git a/core-java-modules/core-java-collections-list-4/src/test/java/com/baeldung/list/tostring/ListToStringUnitTest.java b/core-java-modules/core-java-collections-list-4/src/test/java/com/baeldung/list/tostring/ListToStringUnitTest.java new file mode 100644 index 0000000000..479ccaf92f --- /dev/null +++ b/core-java-modules/core-java-collections-list-4/src/test/java/com/baeldung/list/tostring/ListToStringUnitTest.java @@ -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 arraysAsList = Arrays.asList("ONE", "TWO", "THREE"); + + String commaSeparatedString = String.join(",", arraysAsList); + + assertThat(commaSeparatedString).isEqualTo("ONE,TWO,THREE"); + } + + @Test + void givenAListOfString_whenUsingJava8_thenConvertToStringByUsingStringJoiner() { + + List 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 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 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 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 arraysAsList = Arrays.asList("ONE", "TWO", "THREE"); + + String commaSeparatedString = com.google.common.base.Joiner.on(",") + .join(arraysAsList); + + assertThat(commaSeparatedString).isEqualTo("ONE,TWO,THREE"); + + List 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"); + } + +}