Java 8 : Converting Map>到映射<字符串，字符串[]>

Question

这个问题已经有答案了:

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Map<String, List<String>> parameters;

Map<String, String[]> collect = parameters.entrySet().stream()
                .collect(Collectors.toMap(entry-> entry.getKey(),entry -> entry.getValue().toArray()));

我收到编译器错误无法解析方法“getKey()”

Answer 1

您应该创建一个正确类型的数组(即 String[] 而不是 Object[]):

Map<String, String[]> collect = 
    parameters.entrySet()
              .stream()
              .collect(Collectors.toMap(Map.Entry::getKey,
                                        entry -> entry.getValue().toArray(new String[0])));