import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
public
class Streams1 {
public static
void main(String[] args) {
List<String> stringCollection =
new ArrayList<>();
stringCollection.add(
"ddd2");
stringCollection.add(
"aaa2");
stringCollection.add(
"bbb1");
stringCollection.add(
"aaa1");
stringCollection.add(
"bbb3");
stringCollection.add(
"ccc");
stringCollection.add(
"bbb2");
stringCollection.add(
"ddd1");
// filtering
stringCollection.stream
().filter((s) -> s.startsWith("a")).forEach(System.out::println);
// "aaa2", "aaa1"
// sorting
stringCollection
.stream()
.sorted()
.filter((s) -> s.startsWith("a"))
.forEach(System.out::println);
// "aaa1", "aaa2"
// mapping
stringCollection
.stream()
.map(String::toUpperCase)
.sorted((a, b) -> b.compareTo(a))
.forEach(System.out::println);
// "DDD2", "DDD1", "CCC", "BBB3", "BBB2", "AAA2", "AAA1"
// matching
boolean anyStartsWithA = stringCollection
.stream()
.anyMatch((s) -> s.startsWith("a"));
System.out.println(anyStartsWithA); // true
boolean allStartsWithA = stringCollection
.stream()
.allMatch((s) -> s.startsWith("a"));
System.out.println(allStartsWithA); // false
boolean noneStartsWithZ = stringCollection
.stream()
.noneMatch((s) -> s.startsWith("z"));
System.out.println(noneStartsWithZ); // true
// counting
long startsWithB = stringCollection
.stream()
.filter((s) -> s.startsWith("b"))
.count();
System.out.println(startsWithB); // 3
// reducing
Optional<String> reduced =
stringCollection
.stream()
.sorted()
.reduce((s1, s2) -> s1 + "#" + s2);
reduced.ifPresent(System.out::println);
// "aaa1#aaa2#bbb1#bbb2#bbb3#ccc#ddd1#ddd2"
}
}
转载于:https://www.cnblogs.com/bilaisheng/p/10210937.html
