Java 是否有收集到保留顺序的集合的收集器？
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Is there a Collector that collects to an order-preserving Set?
提问by gvlasov
Collectors.toSet()does not preserve order. I could use Lists instead, but I want to indicate that the resulting collection does not allow element duplication, which is exactly what Setinterface is for.
Collectors.toSet()不保持秩序。我可以改用 Lists，但我想指出生成的集合不允许元素重复，这正是Set接口的用途。
采纳答案by Alexis C.
You can use toCollectionand provide the concrete instance of the set you want. For example if you want to keep insertion order:
您可以使用toCollection并提供所需集合的具体实例。例如，如果您想保持插入顺序：
Set<MyClass> set = myStream.collect(Collectors.toCollection(LinkedHashSet::new));
For example:
例如：
public class Test {
public static final void main(String[] args) {
List<String> list = Arrays.asList("b", "c", "a");
Set<String> linkedSet =
list.stream().collect(Collectors.toCollection(LinkedHashSet::new));
Set<String> collectorToSet =
list.stream().collect(Collectors.toSet());
System.out.println(linkedSet); //[b, c, a]
System.out.println(collectorToSet); //[a, b, c]
}
}
