使用Java8流在嵌套数据结构上创建地图 - java

我正在使用Java 8的流来搜索这段代码的优雅用法: Collection<X> xs = ...; Map<B, A> map = new SomeMap<>(); for (X x : xs) { A a = x.getA(); Collection<B> bs = x.getBs(); for (B b […]