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Terminato capitolo 5 sulle operazioni degli Stream

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This commit is contained in:
Fabio Scotto di Santolo
2019-11-20 20:54:13 +01:00
parent b4ee7f85df
commit 0f0ae0ccec
1 changed files with 45 additions and 3 deletions
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44
modern-java/src/main/java/org/gym/fp/moderjava/StreamTest.java
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@@ -2,6 +2,7 @@ package org.gym.fp.moderjava;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import static java.lang.System.out;
@@ -142,10 +143,51 @@ public class StreamTest {
transactions.stream()
.map(Transaction::getTrader)
.filter(trader -> "Cambridge".equalsIgnoreCase(trader.getCity()))
.distinct() // anche se sul testo non è specificato che dovevano essere diversi
.sorted(Comparator.comparing(Trader::getName))
.collect(Collectors.toList())
.forEach(out::println);
out.println("4)");
String result = transactions.stream()
.map(Transaction::getTrader)
.map(Trader::getName)
.distinct()
.sorted()
.reduce("", (acc, name) -> acc + name);
out.println(result);
out.println("5)");
boolean anyTraderInMilan = transactions.stream()
.map(Transaction::getTrader)
.anyMatch(trader -> "Milan".equalsIgnoreCase(trader.getCity()));
out.println(anyTraderInMilan);
out.println("6)");
transactions.stream()
.filter(transaction -> "Cambridge".equalsIgnoreCase(transaction.getTrader().getCity()))
.forEach(transaction -> out.println(transaction.getValue()));
out.println("7)");
transactions.stream()
.mapToInt(Transaction::getValue)
.max()
.ifPresent(out::println);
out.println("8)");
transactions.stream()
.mapToInt(Transaction::getValue)
.min()
.ifPresent(out::println);
out.println("----------------------------------------");
IntStream.rangeClosed(1, 100)
.boxed()
.flatMap(a -> IntStream.rangeClosed(a, 100)
.mapToObj(b -> new double[]{a, b, Math.sqrt(a * a + b * b)})
.filter(t -> t[2] % 1 == 0)
)
.limit(5)
.forEach(triple -> out.printf("(%.0f, %.0f, %.0f)\n", triple[0], triple[1], triple[2]));
out.println("----------------------------------------");
Stream.iterate(new int[] {0, 1}, t -> new int[] {t[1], t[0] + t[1]})
.limit(20)
.forEach(pair -> out.printf("(%d, %d) ", pair[0], pair[1]));
out.println();
out.println("----------------------------------------");
}