我尝试从流中获取列表,但出现了异常。
下面是一个Movie对象,其中包含一个对象列表。
public class Movie {
private String example;
private List<MovieTrans> movieTranses;
public Movie(String example, List<MovieTrans> movieTranses){
this.example = example;
this.movieTranses = movieTranses;
}
getter and setter
以下是MovieTrans:
public class MovieTrans {
public String text;
public MovieTrans(String text){
this.text = text;
}
getter and setter
我在列表中添加元素:
List<MovieTrans> movieTransList = Arrays.asList(new MovieTrans("Appel me"), new MovieTrans("je t'appel"));
List<Movie> movies = Arrays.asList(new Movie("movie played", movieTransList));
//return a list of MovieTrans
List<MovieTrans> movieTransList1 = movies.stream().map(Movie::getMovieTranses).collect(Collectors.toList());
我有这个编译器错误:
Error:(44, 95) java: incompatible types: inference variable T has incompatible bounds
equality constraints: MovieTrans
lower bounds: java.util.List<MovieTrans>
2条答案
按热度按时间e37o9pze1#
map
调用将
Stream<Movie>
转换为Stream<List<MovieTrans>>
,您可以将其收集为List<List<MovieTrans>>
,而不是List<MovieTrans>
。要获取单个
List<MovieTrans>
,请使用flatMap
:xxhby3vn2#
表达式的类型为
List<List<MovieTrans>>
:它是getMovieTranses
方法的结果的连接。请改用
flatMap
: