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Add implementation for UserServiceImpl #1

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Merged
vitalibutnar merged 1 commit into from
Oct 1, 2021
Merged

Add implementation for UserServiceImpl #1

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57 changes: 44 additions & 13 deletions src/main/java/com/endava/internship/service/UserServiceImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2,68 +2,99 @@

import com.endava.internship.domain.Privilege;
import com.endava.internship.domain.User;
import com.endava.internship.service.UserService;

import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class UserServiceImpl implements UserService {

@Override
public List<String> getFirstNamesReverseSorted(List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().
map(User::getFirstName).
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@vermurachi vermurachi Sep 30, 2021

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There is a reversed() method in Comparator that could be used

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@vitalibutnar vitalibutnar Sep 30, 2021

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Thanks, it's a great idea

sorted(Comparator.reverseOrder()).
collect(Collectors.toList());
}

@Override
public List<User> sortByAgeDescAndNameAsc(final List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().
sorted(Comparator.
comparing(User::getAge, Comparator.reverseOrder()).
thenComparing(User::getFirstName)
).
collect(Collectors.toList());
}

@Override
public List<Privilege> getAllDistinctPrivileges(final List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().
map(User::getPrivileges).
flatMap(Collection::stream).
distinct().
collect(Collectors.toList());
}

@Override
public Optional<User> getUpdateUserWithAgeHigherThan(final List<User> users, final int age) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().
filter(user -> user.getAge() > age).
findFirst();
}

@Override
public Map<Integer, List<User>> groupByCountOfPrivileges(final List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().collect(Collectors.groupingBy(user -> user.getPrivileges().size()));
}

@Override
public double getAverageAgeForUsers(final List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().mapToDouble(User::getAge).average().orElse(-1);
}

@Override
public Optional<String> getMostFrequentLastName(final List<User> users) {
throw new UnsupportedOperationException("Not implemented");
Map<String, Long> map = users.stream().map(User::getLastName).
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@vermurachi vermurachi Sep 30, 2021

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What if we have a list containing one user? should it return Optional.empty?
"optional of most frequent last name (if it encountered at least two times)"

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@vitalibutnar vitalibutnar Sep 30, 2021

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There is a logical error in condition

collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
Long max = map.values().stream().max(Long::compareTo).orElse(0L);
return map.values().stream().filter(val -> val.equals(max)).count() != 1 ? Optional.empty() :
map.entrySet().stream().max(Map.Entry.comparingByValue()).map(Map.Entry::getKey);
}

@Override
public List<User> filterBy(final List<User> users, final Predicate<User>... predicates) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().
filter(
Arrays.stream(predicates).reduce(Predicate::and).orElse(x -> true)
).
collect(Collectors.toList());
}

@Override
public String convertTo(final List<User> users, final String delimiter, final Function<User, String> mapFun) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().map(mapFun).collect(Collectors.joining(delimiter));
}

@Override
public Map<Privilege, List<User>> groupByPrivileges(List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().map(User::getPrivileges).flatMap(Collection::stream).
distinct().
collect(Collectors.toMap(
privilege -> privilege,
privilege -> users.stream().filter(user -> user.getPrivileges().contains(privilege)).collect(Collectors.toList())
)
);
}

@Override
public Map<String, Long> getNumberOfLastNames(final List<User> users) {
throw new UnsupportedOperationException("Not implemented");
return users.stream().collect(Collectors.groupingBy(User::getLastName, Collectors.counting()));
}
}
}