java8并行流处理实例
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import java.util.Arrays;
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import java.util.LinkedHashMap;
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import java.util.Map;
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import java.util.function.Function;
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import java.util.stream.Collectors;
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import java.util.stream.LongStream;
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import java.util.stream.Stream;
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/**
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* @Auther: jack
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* @Date: 2018/7/24 11:05
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* @Description: jdk8 并行流处理
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*/
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public class StreamParallel {
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public static void main(String[] args) {
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//rangeClosed包含末尾数据
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long sum=LongStream.rangeClosed(1,10000000L).parallel().reduce(0,Long::sum);
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System.out.println(sum);
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//range不包含末尾节点
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sum=LongStream.range(1,10000000L).parallel().reduce(0,Long::sum);
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System.out.println(sum);
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//求和reduce()
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System.out.println(Stream.of(1,2,3,4).reduce((sum2,item)->{
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return sum2+item;
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}).get());
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System.out.println(Stream.of(1,2,3,4).reduce(Integer::sum).get());
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//求最大值reduce()
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System.out.println(Stream.of(1,2,3,4).reduce(100,(a,b)->Math.max(a, b)));
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System.out.println(Stream.of(1,2,3,4).reduce(Integer::max).get());
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//去重distinct()
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System.out.println(Arrays.asList("a", "b", "c", "d", "a", "b", "c")
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.stream()
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.distinct()
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.collect(Collectors.toList())
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);
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//统计分组
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System.out.println(Arrays.asList("apple", "apple", "banana",
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"apple", "orange", "banana", "papaya")
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.stream()
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.collect(Collectors.groupingBy(Function.identity(),Collectors.counting()))
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);
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//统计排序
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Map
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Arrays.asList("apple", "apple", "banana", "apple", "orange", "banana", "papaya")
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.stream()
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.collect(Collectors.groupingBy(Function.identity(),Collectors.counting()))
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.entrySet()
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.stream()
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.sorted(Map.Entry.
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.forEachOrdered(e->sortMap.put(e.getKey(),e.getValue()));
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System.out.println(sortMap);
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}
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}
运行结果：
