数组 和 流
原始类型数组 to Stream
// int/long/double
int[] ints = new int[]{1 ,2 ,3};
Stream<Integer> integerStream = Arrays.stream(ints).boxed();
// char
char[] chars = new char[]{'a', 'b', 'c'};
Stream<Character> characterStream = IntStream.range(0, chars.length).mapToObj(i -> chars[i]);
// 如果是String
String str = "12345678";
Stream<Character> characterStream = str.chars().mapToObj(c -> (char)c);