添加对集合的响应<String>

Question

Set<String> response = null;
Set<String> success = null;
for (String country : countrys) {

    response = service.method(country);

    if (response != null) {

        success = response;
    }
}

这里service.methodreturns一个Set<String>。我想将每个循环的响应添加到成功集。

现在，这段代码只是存储最后一个循环成功的响应。有人可以尽快帮忙吗？

Answer 1

您可以使用 addAll(Collection<? extends E> c) 方法 (see spec):

    Set<String> response = null;
    Set<String> success = new HashSet<>();
    for (String country : countrys) {

        response = service.method(country);

        if (response != null) {
            success.addAll(response);
        }
    }

请记住，您需要先将 success 初始化为空集（例如 HashSet）。否则你会运行变成NullPointerException.

添加对集合的响应<String>

Add response to a Set<String>

java

collections

for-loop

set