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Copy pathStreamsLesson.java
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70 lines (64 loc) · 2.98 KB
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package java8;
import java.util.*;
import java.util.function.BinaryOperator;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import static java.util.Arrays.asList;
public class StreamsLesson {
public static void main(String[] args) {
List<String> list = new ArrayList<>();
list.add("one");
list.add("two");
for(String s : list) {
System.out.println(s);
}
Iterator<String> iterator = list.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
Stream<String> stringStream = list.stream();
stringStream.forEach(x -> System.out.println(x));
for(String s : list) {
if(s.equals("one")) {
System.out.println(s);
}
}
stringStream = list.stream();
stringStream.filter(x -> x.equals("one")).forEach(x -> System.out.println(x));//only once
stringStream = list.stream();
Stream<String> stringStream1 = stringStream.filter((x) -> {
System.out.println("hello");
return x.equals("one");
});//lazy
stringStream1.forEach(x -> System.out.println(x));//eager
Set<String> st = Stream.of("one", "two").collect(Collectors.toSet());//eager
List<String> list1 = Stream.of("one", "two").map(x -> x.toUpperCase()).collect(Collectors.toList());
List<String> list2 = Stream.of("one", "two").filter(x -> x.equals("one")).collect(Collectors.toList());
List<String> list3 = Stream.of(asList("one", "two"), asList("three", "four")).flatMap(x -> x.stream()).collect(Collectors.toList());
int value = Stream.of(1, 2).min(Comparator.comparing(x -> x)).get();
int value2 = Stream.of(1, 2).max(Comparator.comparing(x -> x)).get();
int count = Stream.of(1, 2, 3).reduce(0, (acc, element) -> acc + element);
int accomulator = 0;
for(int element : new int[]{1,2,3}) {
accomulator += element;
}
BinaryOperator<Integer> accumulator = (acc, element) -> acc + element;
int count2 = accumulator.apply(
accumulator.apply(
accumulator.apply(0, 1),
2),
3);
Stream.of("one", "two").sorted().collect(Collectors.toList());
Stream.of("one", "two").limit(1).collect(Collectors.toList());
Stream.of("one", "one").distinct().collect(Collectors.toList());
Stream.of("one", "one").skip(1).collect(Collectors.toList());
Stream.of("one", "two").filter(x -> x.equals("one")).findAny().get();
Stream.of("one", "two").filter(x -> x.equals("one")).findAny().isPresent();
Stream.of(1, 2).mapToInt(x -> x).sum();
Stream.of(1, 2).count();
Stream.of("one", "two").peek(x -> x.toUpperCase()).findFirst().get();
IntStream intStream = Stream.of(1, 2).mapToInt(x -> x);
intStream.summaryStatistics().getAverage();
}
}