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refactor unit test into utility class

This commit is contained in:
joe zhang 2020-07-12 16:19:08 +08:00
parent 4f987c9198
commit 7cbb0833d4
2 changed files with 83 additions and 65 deletions
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70
java-collections-conversions-2/src/main/java/com/baeldung/convertlisttomap/ListToMapConverter.java Normal file
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@ -0,0 +1,70 @@
package com.baeldung.convertlisttomap;
import java.util.List;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;
/**
* Convert a string list to a map whose key is the string's length and value is the collection with same length.
* Give a list {"Baeldung", "is", "very", "cool"}.
* After conversion we'll get a map like:
* {8 : ["Baeldung"], 2 : ["is"], 4 : ["very", "cool"]}.
*
* @author leasy.zhang
*
*/
public class ListToMapConverter {
public Map<Integer, List<String>> groupingByStringLength(List<String> source,
Supplier<Map<Integer, List<String>>> mapSupplier,
Supplier<List<String>> listSupplier) {
return source.stream()
.collect(Collectors.groupingBy(String::length, mapSupplier, Collectors.toCollection(listSupplier)));
}
public Map<Integer, List<String>> streamCollectByStringLength(List<String> source,
Supplier<Map<Integer, List<String>>> mapSupplier,
Supplier<List<String>> listSupplier) {
BiConsumer<Map<Integer, List<String>>, String> accumulator = (response, element) -> {
Integer key = element.length();
List<String> values = response.getOrDefault(key, listSupplier.get());
values.add(element);
response.put(key, values);
};
BiConsumer<Map<Integer, List<String>>, Map<Integer, List<String>>> combiner = (res1, res2) -> {
res1.putAll(res2);
};
return source.stream()
.collect(mapSupplier, accumulator, combiner);
}
public Map<Integer, List<String>> collectorToMapByStringLength(List<String> source,
Supplier<Map<Integer, List<String>>> mapSupplier,
Supplier<List<String>> listSupplier) {
Function<String, Integer> keyMapper = String::length;
Function<String, List<String>> valueMapper = (element) -> {
List<String> collection = listSupplier.get();
collection.add(element);
return collection;
};
BinaryOperator<List<String>> mergeFunction = (existing, replacement) -> {
existing.addAll(replacement);
return existing;
};
return source.stream()
.collect(Collectors.toMap(keyMapper, valueMapper, mergeFunction, mapSupplier));
}
}

78
java-collections-conversions-2/src/test/java/com/baeldung/convertlisttomap/ListToMapUnitTest.java
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@ -1,6 +1,5 @@
package com.baeldung.convertlisttomap;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import java.util.ArrayList;
@ -8,89 +7,38 @@ import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import org.junit.Before;
import org.junit.Test;
public class ListToMapUnitTest {
private ListToMapConverter converter;
private List<String> source;
@Before
public void setUp() {
converter = new ListToMapConverter();
source = Arrays.asList("List", "Map", "Set", "Tree");
}
@Test
public void givenAList_whenConvertWithJava8GroupBy_thenReturnMap() {
List<String> strings = Arrays.asList("List", "Map", "Set", "Tree");
Map<Integer, List<String>> convertedMap = new HashMap<>();
Supplier<List<String>> listSupplier = ArrayList::new;
Supplier<Map<Integer, List<String>>> mapFactory = HashMap::new;
convertedMap = strings.stream()
.collect(Collectors.groupingBy(String::length, mapFactory, Collectors.toCollection(listSupplier)));
assertEquals(2, convertedMap.size());
Map<Integer, List<String>> convertedMap = converter.groupingByStringLength(source, HashMap::new, ArrayList::new);
assertTrue(convertedMap.get(3)
.contains("Map"));
}
@Test
public void givenAList_whenConvertWithJava8Collect_thenReturnMap() {
List<String> strings = Arrays.asList("List", "Map", "Set", "Tree");
Map<Integer, List<String>> convertedMap = new HashMap<>();
Supplier<Map<Integer, List<String>>> mapFactory = HashMap::new;
Supplier<List<String>> listSupplier = ArrayList::new;
BiConsumer<Map<Integer, List<String>>, String> accumulator = (response, element) -> {
Integer key = element.length();
List<String> values = response.getOrDefault(key, listSupplier.get());
values.add(element);
response.put(key, values);
};
BiConsumer<Map<Integer, List<String>>, Map<Integer, List<String>>> combiner = (res1, res2) -> {
res1.putAll(res2);
};
convertedMap = strings.stream()
.collect(mapFactory, accumulator, combiner);
assertEquals(2, convertedMap.size());
Map<Integer, List<String>> convertedMap = converter.streamCollectByStringLength(source, HashMap::new, ArrayList::new);
assertTrue(convertedMap.get(3)
.contains("Map"));
}
@Test
public void givenAList_whenConvertWithCollectorToMap_thenReturnMap() {
List<String> strings = Arrays.asList("List", "Map", "Set", "Tree");
Map<Integer, List<String>> convertedMap = new HashMap<>();
Supplier<Map<Integer, List<String>>> mapFactory = HashMap::new;
Supplier<List<String>> listSupplier = ArrayList::new;
Function<String, Integer> keyMapper = String::length;
Function<String, List<String>> valueMapper = (element) -> {
List<String> collection = listSupplier.get();
collection.add(element);
return collection;
};
BinaryOperator<List<String>> mergeFunction = (existing, replacement) -> {
existing.addAll(replacement);
return existing;
};
convertedMap = strings.stream()
.collect(Collectors.toMap(keyMapper, valueMapper, mergeFunction, mapFactory));
assertEquals(2, convertedMap.size());
Map<Integer, List<String>> convertedMap = converter.collectorToMapByStringLength(source, HashMap::new, ArrayList::new);
assertTrue(convertedMap.get(3)
.contains("Map"));
}