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// === Setup to make the code runnable === | |
@Grab( 'com.bloidonia:groovy-stream:0.6.2' ) | |
@Grab( 'org.codehaus.gpars:gpars:1.1.0' ) | |
import groovy.transform.Immutable | |
import groovy.stream.Stream | |
import groovyx.gpars.GParsPool | |
def file = new File('persons.csv') | |
file.delete() // to reset from last time | |
file.createNewFile() | |
file << '''name, age, city, country | |
Ivar Østhus, 28, Sandnes, Norway | |
Theo, 13, Skedsmo, Norway | |
Viswanathan Anand, 43, Mayiladuthurai, India | |
Magnus Carlsen, 22, Tønsberg, Norway | |
''' | |
@Immutable class Person { String name; int age; String city; String country } | |
def persons = [ | |
new Person("Ivar", 28, "Sandnes", "Norge"), | |
new Person("Theo", 13, "Skedsmo", "Norge"), | |
new Person("Kjetil", 40, "Skedsmo", "Norge") | |
] | |
// =======JAVA in comments, Groovy is runnable======= | |
// Arrays.asList(1,2,3,4,5).forEach(System.out::println) | |
(1..5).each { println it } | |
// Arrays.asList(1, 2, 3, 4, 5, 6).stream().filter(n -> n % 2 == 0).mapToInt(n -> n * 2).sum() | |
Stream.from(1..6).filter { it % 2 == 0 }.sum() | |
// persons.stream().filter(p -> p.getAge() > 17) | |
Stream.from(persons).filter { it.age > 17 } | |
// persons.stream().filter(p -> p.getAge() > 17).sorted((p1, p2) -> p1.getAge() - p2.getAge()); | |
Stream.from(persons).filter { it.age > 17 }.sort{ it.age } | |
// persons.stream().filter(p -> p.getCity().equals("Sandnes")).mapToInt(p -> p.getAge()).average(); | |
[Stream.from(persons).filter{ it.city =="Sandnes" }*.age].collect{ it.sum() / it.size() }[0] | |
// persons.stream().map(Person::getName).collect(toSet()) | |
Stream.from(persons)*.name.toSet() | |
// persons.stream().collect(groupingBy(Person::getAge, mapping(Person::getName, toList())) | |
Stream.from(persons.groupBy { it.age }).map { [(it.key) : it.value*.name ] } | |
// public static Function<String, Person> toPerson = (line) -> { | |
// String[] p = line.split(", "); | |
// return new Person(p[0], Integer.parseInt(p[1]), p[2], p[3]); | |
// }; | |
def toPerson = { line -> | |
def p = line.split(", "); | |
new Person(p[0], p[1].toInteger(), p[2], p[3]) | |
} | |
// public static Predicate<Person> isAdult = p -> p.getAge() > 17; | |
def isAdult = { it.age > 17 } | |
// InputStream is = new FileInputStream(new File("persons.csv")); | |
// BufferedReader br = new BufferedReader(new InputStreamReader(is)); | |
// List<Person> persons = br.lines() | |
// .substream(1) | |
// .map(toPerson) | |
// .filter(isAdult) | |
// .limit(50) | |
// .collect(toList()); | |
persons = Stream.from(new File('persons.csv').readLines() | |
.drop(1)) | |
.map(toPerson) | |
.filter(isAdult) | |
.take(50) | |
.toList() | |
// OptionalDouble average = persons.parallelStream().filter(p -> p.getCity().equals("Sandnes")).mapToInt(p -> p.getAge()).average(); | |
GParsPool.withPool { | |
[persons.parallel.filter{ it.city =="Sandnes" }.map {it.age}.getCollection()].collect {it.sum() / it.size() }[0] | |
} |
Men til slutt må man huske på at syntax ikke er alt, det er bare sukkeret på toppen som gjør det extra sweet.
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Må si groovy bli overlegent på syntax.
Men det er vel riktige å sammenligne Stream.from() med IntStream (ikke Arrays.asList)? F.eks: