过滤类org.jdom.ContentList $ FilterList以获取Element的实例

Question

def printTree(e: Element, depth: Int){
    System.out.println("Number of children in element : " ,e.getChildren().getClass());
    System.out.println(StringUtils.repeat("\t", depth) + e.getText());
    e.getChildren().stream().filter(e.isInstanceOf[Element]);
}

错误：类型不匹配 发现[错误]：布尔值 [错误]必需：？0 =>布尔值，其中类型为？0