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Drozdov Igor stream part2 #70

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2389682
part2.1
Jul 11, 2017
6b15bd6
temp
eye-dee Jul 12, 2017
a480bfb
ex 2 completed
Jul 12, 2017
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93 changes: 75 additions & 18 deletions src/test/java/part2/exercise/CollectorsExercise1.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,17 +6,13 @@
import org.junit.Test;

import java.util.*;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.*;
import static org.junit.Assert.assertEquals;

public class CollectorsExercise1 {

Expand Down Expand Up @@ -53,16 +49,41 @@ public int getDuration() {

// With the longest duration on single job
private Map<String, Person> getCoolestByPosition(List<Employee> employees) {
// First option
// Collectors.maxBy
// Collectors.collectingAndThen
// Collectors.groupingBy

// Second option
// Collectors.toMap
// iterate twice: stream...collect(...).stream()...
// TODO
throw new UnsupportedOperationException();
Map<String, Person> collect = employees.stream()
.flatMap(
this::toPersonPositionDuration
)
.collect(
groupingBy(
PersonPositionDuration::getPosition,
collectingAndThen(maxBy(Comparator.comparing(PersonPositionDuration::getDuration)), p -> p.get().getPerson())
)
);

Map<String, Person> collect1 = employees.stream()
.flatMap(this::toPersonPositionDuration)
.collect(Collectors.toMap(
PersonPositionDuration::getPosition,
Function.identity(),
BinaryOperator.maxBy(Comparator.comparing(PersonPositionDuration::getDuration))
))
.entrySet().stream()
.collect(
toMap(
Map.Entry::getKey,
t -> t.getValue().getPerson()
)
);


assertEquals(collect, collect);

return collect;
}

private Stream<? extends PersonPositionDuration> toPersonPositionDuration(Employee employee) {
return employee.getJobHistory().stream()
.map(jobHistoryEntry -> new PersonPositionDuration(employee.getPerson(), jobHistoryEntry.getPosition(), jobHistoryEntry.getDuration()));
}

@Test
Expand All @@ -75,8 +96,44 @@ public void getTheCoolestOne2() {
// With the longest sum duration on this position
// { John Doe, [{dev, google, 4}, {dev, epam, 4}] } предпочтительнее, чем { A B, [{dev, google, 6}, {QA, epam, 100}]}
private Map<String, Person> getCoolestByPosition2(List<Employee> employees) {
// TODO
throw new UnsupportedOperationException();
return employees.stream()
.flatMap(this::toExclusivePersonPositionDuration)
.collect(
groupingBy(
PersonPositionDuration::getPosition,
collectingAndThen(maxBy(Comparator.comparing(PersonPositionDuration::getDuration)), p -> p.get().getPerson())
)
);
/*.collect(
toMap(
PersonPositionDuration::getPosition,
Function.identity(),
(p1, p2) -> p1.getDuration() > p2.getDuration() ? p1 : p2
)
).entrySet()
.stream()
.collect(
toMap(
Map.Entry::getKey,
e -> e.getValue().getPerson()
)
);*/
}

private Stream<? extends PersonPositionDuration> toExclusivePersonPositionDuration(Employee employee) {
return employee.getJobHistory()
.stream()
.collect(
toMap(JobHistoryEntry::getPosition,
JobHistoryEntry::getDuration,
(d1, d2) -> d1 + d2
)
)
.entrySet()
.stream()
.map(
entry -> new PersonPositionDuration(employee.getPerson(), entry.getKey(), entry.getValue())
);
}

private List<Employee> getEmployees() {
Expand Down
100 changes: 74 additions & 26 deletions src/test/java/part2/exercise/CollectorsExercise2.java
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,8 +1,5 @@
package part2.exercise;

import data.Employee;
import data.JobHistoryEntry;
import data.Person;
import org.junit.Test;

import java.util.*;
Expand All @@ -16,7 +13,7 @@
import java.util.stream.IntStream;
import java.util.stream.Stream;

import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.*;

public class CollectorsExercise2 {

Expand All @@ -31,20 +28,20 @@ private static String generateString() {
.collect(Collectors.joining());
}

private static String[] generateStringArray(int length) {
private static String[] generateStringArray(final int length) {
return Stream.generate(CollectorsExercise2::generateString)
.limit(length)
.toArray(String[]::new);
}

public static String pickString(String[] array) {
private static String pickString(final String[] array) {
return array[ThreadLocalRandom.current().nextInt(array.length)];
}

public static class Key {
private final String id;

public Key(String id) {
public Key(final String id) {
this.id = id;
}

Expand All @@ -53,14 +50,13 @@ public String getId() {
}

@Override
public boolean equals(Object o) {
public boolean equals(final Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;

Key key = (Key) o;
final Key key = (Key) o;

return id.equals(key.id);

}

@Override
Expand All @@ -72,7 +68,7 @@ public int hashCode() {
public static class Value {
private final String keyId;

public Value(String keyId) {
public Value(final String keyId) {
this.keyId = keyId;
}

Expand All @@ -85,7 +81,7 @@ public static class Pair {
private final Key key;
private final Value value;

public Pair(Key key, Value value) {
public Pair(final Key key, final Value value) {
this.key = key;
this.value = value;
}
Expand All @@ -99,7 +95,7 @@ public Value getValue() {
}
}

public static List<Pair> generatePairs(int idCount, int length) {
public static List<Pair> generatePairs(final int idCount, final int length) {
final String[] ids = generateStringArray(idCount);

return Stream.generate(() -> new Pair(new Key(pickString(ids)), new Value(pickString(ids))))
Expand All @@ -112,7 +108,7 @@ private static class SubResult {
private final Map<String, List<Key>> knownKeys;
private final Map<String, List<Value>> valuesWithoutKeys;

public SubResult(Map<Key, List<Value>> subResult, Map<String, List<Key>> knownKeys, Map<String, List<Value>> valuesWithoutKeys) {
public SubResult(final Map<Key, List<Value>> subResult, final Map<String, List<Key>> knownKeys, final Map<String, List<Value>> valuesWithoutKeys) {
this.subResult = subResult;
this.knownKeys = knownKeys;
this.valuesWithoutKeys = valuesWithoutKeys;
Expand All @@ -139,7 +135,7 @@ public MapPair() {
this(new HashMap<>(), new HashMap<>());
}

public MapPair(Map<String, Key> keyById, Map<String, List<Value>> valueById) {
public MapPair(final Map<String, Key> keyById, final Map<String, List<Value>> valueById) {
this.keyById = keyById;
this.valueById = valueById;
}
Expand All @@ -154,9 +150,9 @@ public Map<String, List<Value>> getValueById() {
}

private static <K, V, M extends Map<K, V>>
BinaryOperator<M> mapMerger(BinaryOperator<V> mergeFunction) {
BinaryOperator<M> mapMerger(final BinaryOperator<V> mergeFunction) {
return (m1, m2) -> {
for (Map.Entry<K, V> e : m2.entrySet()) {
for (final Map.Entry<K, V> e : m2.entrySet()) {
m1.merge(e.getKey(), e.getValue(), mergeFunction);
}
return m1;
Expand All @@ -170,7 +166,32 @@ public void collectKeyValueMap() {
// В два прохода
// final Map<String, Key> keyMap1 = pairs.stream()...

final Map<String, Key> idToKey = pairs.stream()
.collect(
toMap(
pair -> pair.getKey().getId(),
Pair::getKey
)
);

// final Map<String, List<Value>> valuesMap1 = pairs.stream()...
final Map<Key, List<Value>> keyValuesMap1 = pairs.stream()
.collect(groupingBy(
pair -> pair.getValue().getKeyId(),
collectingAndThen(mapping(Pair::getValue, toList()), Function.identity())
))
.entrySet().stream()
.collect(
toMap(
pair -> idToKey.get(pair.getKey()),
Map.Entry::getValue,
(l1, l2) -> {
l1.addAll(l2);
return l1;
}
)
);


// В каждом Map.Entry id ключа должно совпадать с keyId для каждого значения в списке
// final Map<Key, List<Value>> keyValuesMap1 = valueMap1.entrySet().stream()...
Expand All @@ -180,20 +201,39 @@ public void collectKeyValueMap() {
.collect(new Collector<Pair, MapPair, MapPair>() {
@Override
public Supplier<MapPair> supplier() {
// TODO
throw new UnsupportedOperationException();
return MapPair::new;
}

@Override
public BiConsumer<MapPair, Pair> accumulator() {
// TODO add key and value to maps
throw new UnsupportedOperationException();
return (mapPair, pair) -> {
mapPair.getKeyById().put(pair.getKey().getId(), pair.getKey());
mapPair.getValueById().merge(
pair.getValue().getKeyId(),
Collections.singletonList(pair.getValue()),
this::listMerger
);
};
}

private List<Value> listMerger(List<Value> values, List<Value> values1) {
values.addAll(values1);
return values;
}

@Override
public BinaryOperator<MapPair> combiner() {
// TODO use mapMerger
throw new UnsupportedOperationException();
return (p1, p2) -> {
BinaryOperator<Map<String, Key>> toKey = mapMerger((k1, k2) -> k1);
BinaryOperator<Map<String, List<Value>>> toValues = mapMerger((v1, v2) -> {
v1.addAll(v2);
return v1;
});

toKey.apply(p1.getKeyById(),p2.getKeyById());
toValues.apply(p1.getValueById(),p2.getValueById());
return new MapPair(p1.getKeyById(),p2.getValueById());
};
}

@Override
Expand All @@ -212,15 +252,23 @@ public Set<Characteristics> characteristics() {
final Map<String, Key> keyMap2 = res2.getKeyById();
final Map<String, List<Value>> valuesMap2 = res2.getValueById();

// final Map<Key, List<Value>> keyValuesMap2 = valueMap2.entrySet().stream()...

final Map<Key, List<Value>> keyValuesMap2 = valuesMap2.entrySet().stream()
.collect(
toMap(
pair -> idToKey.get(pair.getKey()),
Map.Entry::getValue,
(l1, l2) -> {
l1.addAll(l2);
return l1;
}
)
);
// Получение результата сразу:

final SubResult res3 = pairs.stream()
.collect(new Collector<Pair, SubResult, SubResult>() {
@Override
public Supplier<SubResult> supplier() {
// TODO
throw new UnsupportedOperationException();
}

Expand Down