使用现有列表中的HashMap创建一个包含值的新列表

Question

我想从现有列表中创建一个新的Map列表.

我得到一个ArrayList如下结构;

ArrayList
         0 = {LinkedHashMap}
                   0 = {LinkedHashMapEntry} "name" --> "value"
                   1 = {LinkedHashMapEntry} "surname" --> "value"
         1 = {LinkedHashMap}
                   0 = {LinkedHashMapEntry} "name" --> "value"
                   1 = {LinkedHashMapEntry} "surname" --> "value"
         ....

我想要做的是将所有名称值作为新列表.

List<String> allNames = ....

有没有办法使用Java Stream获取此列表？

Answer 1

是:

List<String> allNames =
    list.stream() // this creates a Stream<LinkedHashMap<String,String>>
        .map(m->m.get("name")) // this maps the original Stream to a Stream<String>
                               // where each Map of the original Stream in mapped to the
                               // value of the "name" key in that Map
        .filter(Objects::nonNull) // this filters out any null values
        .collect(Collectors.toList()); // this collects the elements
                                       // of the Stream to a List