Collectors.toMap()中的错误报告是否已损坏？

Question

List<String> strings = Arrays.asList("3","55","3");
Map<String,Integer> map = strings
    .stream()
    .collect(Collectors.toMap(s ->s, s -> s.length()));

回报

java.lang.IllegalStateException: Duplicate key 1

我希望在哪里复制密钥3

Answer 1

此问题已在 Java 9 中修复。现在错误消息是正确的：

java.lang.IllegalStateException: Duplicate key 3 (attempted merging values 1 and 1)