我有这个字符集流：
Stream<Set<Character>> characterSet
现在，我想将此流转换为简单的字符集，然后执行以下操作：
Set<Character> newSet = characterSet.collect(Collectors.toSet());
但是，我收到此错误：
Incompatible types. Required Set<Character> but 'collect' was inferred to R: no instance(s) of type variable(s) exist so that Set<Character> conforms to Character inference variable T has incompatible bounds: equality constraints: Character lower bounds: Set<Character>.
我该如何解决？谢谢！
如下进行：
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class Main {
public static void main(String[] args) {
Set<Character> newSet = Stream
.of(Set.of(Character.valueOf('A'), Character.valueOf('B')),
Set.of(Character.valueOf('C'), Character.valueOf('D')))
.flatMap(s -> s.stream()).collect(Collectors.toSet());
System.out.println(newSet);
}
}
输出：
[A, B, C, D]