lista de strings

.streams

// {
package streams;

import java.util.*;

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

public class FlatMap {
// }

public static List<String> transform(List<List<String>> collection) {
	List<String> newCollection = new ArrayList<>();
	for (List<String> subCollection : collection) {
		for (String value : subCollection) {
			newCollection.add(value);
		}
	}
	return newCollection;
}

// {
}
// }

1- Transformar a cillection no strea

// {
package streams;

import java.util.*;

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

public class FlatMap {
// }

public static List<String> transform(List<List<String>> collection) {
    return collection.stream().flatMap(List::stream).collect( toList());

}

// {
}
// }

Tranformar cada elemento do array para um novo stream

comparator

max - object

Comparator comparing:: getAge

// {
package streams;

import java.util.*;

public class MaxAndComparator {
// }

	public static Person getOldestPerson(List<Person> people) {

		Person oldestPerson = new Person("", 0);
		for (Person person : people) {
			if (person.getAge() > oldestPerson.getAge()) {
				oldestPerson = person;
			}
		}
		return oldestPerson;
	}

// {
}
// }

// {
package streams;

import java.util.*;

public class MaxAndComparator {
// }

	public static Person getOldestPerson(List<Person> people) {
        return people.stream().max( Comparator.comparing(Person::getAge)).orElse(null);
	
	}

// {
}
// }

// {
package streams;

import java.util.*;

public class SumAndReduce {
// }

	public static int calculate(List<Integer> numbers) {
		int total = 0;
		 for (int number : numbers) {
		 	total += number;
		 }
		 return total;return numbers.stream().reduce(0, (total, number) -> total + number); 
	}

// {
}
// }

// {
package streams;

import java.util.*;

public class SumAndReduce {
// }

	public static int calculate(List<Integer> numbers) {
		 return total;return numbers.stream().reduce(0, (total, number) -> total + number);
///return numbers.stream().reduce(0, Integer::sum); 
	}

// {
}
// }

reduce elemento dentidade lambda