java - 如何避免警告类型安全 : Unchecked cast from Object to ArrayList<Facility>

Question

以下代码段会导致 Eclipse 中倒数第二行的警告“类型安全:未经检查的从对象到 ArrayList 的转换”。只是想知道我能做些什么来改进它。该代码用于从 xml 文件中读取对象。

private List<Facility> getFacilityCodes() {
    InputStream in = this.getClass().getResourceAsStream("./resources/facility.xml");
    String xml = convertStreamToString(in);
    XStream xstream = new XStream(new StaxDriver());
    xstream.alias("Facility", Facility.class);
    xstream.alias("Facilities", List.class);
    ArrayList<Facility> facilities = (ArrayList<Facility>) xstream.fromXML(xml);
    return facilities;
}

Answer 1

问题是只要返回的对象是一个ArrayList就会转换成功，但是因为删除不能保证每个元素都是一个Facility .如果您愿意，您可以自己做。

ArrayList<Facility> facilities =
    ((ArrayList<?>) xstream.fromXML(xml)).stream()
                                         .filter(Facility.class::isInstance)
                                         .map(Facility.class::cast)
                                         .collect(Collectors.toCollection(ArrayList::new));