JAVA

java remove duplicates from list by property

import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toCollection;

...
List<Employee> unique = employee.stream()
                                .collect(collectingAndThen(toCollection(() -> new TreeSet<>(comparingInt(Employee::getId))),
                                                           ArrayList::new));

java remove duplicates from list by field

List<Obj> list = ...; // list contains multiple objects
Collection<Obj> nonDuplicateCollection = list.stream()
        .collect(Collectors.toMap(Obj::generateUniqueKey, Function.identity(), (a, b) -> a))
        .values();