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Stream流式编程用例

news 2025/7/9 9:20:51

Stream流式编程用例：

filter, map, flatmap, limit, skip, sort, distinct, collect, reduce, summary statistics

public class StreamTest {public static void main(String[] args) {//filterStream<Integer> stream = Stream.of(1, 2, 3, 4, 5);Stream<Integer> filteredStream = stream.filter(n -> n % 2 == 0); // 过滤出偶数
//        filteredStream.forEach(System.out::println);//mapStream<String> stream2 = Stream.of("apple", "banana", "cherry");Stream<Integer> mappedStream = stream2.map(String::length); // 映射为单词长度
//        mappedStream.forEach(System.out::println);//flatmapList<List<Integer>> nestedList = Arrays.asList(Arrays.asList(1, 2),Arrays.asList(3, 4),Arrays.asList(5, 6));Stream<Integer> flattenedStream = nestedList.stream().flatMap(List::stream);
//        flattenedStream.forEach(System.out::println);//limitStream<Integer> stream3 = Stream.of(1, 2, 3, 4, 5);Stream<Integer> limitedStream = stream3.limit(3); // 只保留前 3 个元素
//        limitedStream.forEach(System.out::println);//skipStream<Integer> stream4 = Stream.of(1, 2, 3, 4, 5);Stream<Integer> skippedStream = stream4.skip(2); // 跳过前 2 个元素
//        skippedStream.forEach(System.out::println);//sortStream<Integer> stream5 = Stream.of(5, 2, 4, 1, 3);Stream<Integer> sortedStream = stream5.sorted(); // 自然顺序排序
//        sortedStream.forEach(System.out::println);//distinctStream<Integer> stream6 = Stream.of(1, 2, 2, 3, 3, 3);Stream<Integer> distinctStream = stream6.distinct(); // 去重
//        distinctStream.forEach(System.out::println);//collectStream<String> stream7 = Stream.of("apple", "banana", "cherry");List<String> collectedList = stream7.toList(); // 收集为 List
//        collectedList.forEach(System.out::println);//reduce 规约Stream<Integer> stream8 = Stream.of(1, 2, 3, 4, 5);Optional<Integer> sum = stream8.reduce(Integer::sum); // 对所有元素求和
//        System.out.println("sum: " + sum);//summary statisticsIntStream stream9 = IntStream.of(1, 2, 3, 4, 5);IntSummaryStatistics stats = stream9.summaryStatistics();System.out.println("Count: " + stats.getCount());System.out.println("Min: " + stats.getMin());System.out.println("Max: " + stats.getMax());System.out.println("Sum: " + stats.getSum());System.out.println("Average: " + stats.getAverage());}
}