1、 使用IntStream实现的几种方法
intStream文档:https://docs.oracle.com/javase/8/docs/api/java/util/stream/IntStream.html
1) IntStream.range
public static List<Integer> getIndexList(String s, char c) {
return IntStream.range(0, s.length())
.filter(index -> s.charAt(index) == c)
.boxed()
.collect(Collectors.toList());
}
2) IntStream.iterate
public static List<Integer> getIndexList(String s, char c) {
return IntStream.iterate(s.indexOf(c), i -> s.indexOf(c, i + 1))
.takeWhile(i -> i > -1)
.boxed()
.collect(Collectors.toList());
}
或
private static List<Integer> getIndexList(String word, char c) {
return IntStream
.iterate(word.indexOf(c), index -> index >= 0, index -> word.indexOf(c, index + 1))
.boxed()
.collect(Collectors.toList());
}
2、使用Stream.of实现
Stream.of("Hello world!")
.map(Scanner::new)
.flatMap(s -> s.findAll("l"))
.map(mr -> mr.start())
.forEach(System.out::println);