ex.java

public class _Stream {

	public static void main(String[] args) {
		List<Person> people = List.of(
				new Person("Jonh", MALE),
				new Person("Maria", FEMALE),
				new Person("Aisha", FEMALE),
				new Person("Alex", MALE),
				new Person("Alice", FEMALE),
				new Person("Bob", PREFER_NOT_TO_SAY)
				);
//		people.stream()
//			.map(person -> person.name)
//			.collect(Collectors.toSet())
//			.forEach(System.out::println);
//		
//	people.stream()
//		.map(person -> person.name)
//		.mapToInt(String::length)
//		.forEach(System.out::println);
//	
//	boolean containsOnlyFemales = people.stream()
//		  .allMatch(person -> FEMALE.equals(person.gender));
//	
//		System.out.println(containsOnlyFemales);
		
		String dto1 = null;
		String dto2 = "";
		people.stream()
			.filter(dto1 != null ? e -> e.name.equals("Jonh") : e -> true)
			.filter(dto2 != null ? person -> FEMALE.equals(person.gender) : person -> true)
			.collect(Collectors.toList()).forEach(System.out::println);
		
	}
	

	static class Person {
		private final String name;
		private final Gender gender;

		public Person(String name, Gender gender) {
			this.name = name;
			this.gender = gender;
		}

		@Override
		public String toString() {
			return "Person {name=" + name + ", gender=" + gender + "}";
		}

	}

	enum Gender {
		MALE, FEMALE, PREFER_NOT_TO_SAY
	}