为什么 Apache commons csv 解析器将唯一数据附加到第二个结果集中？

Question

我在一个目录中有 2 个 CSV 文件（district1.csv、district2.csv），每个文件都包含一列schoolCode。当我使用 Apache commons CSV 库读取两个 CSV 文件时，我正在读取schoolCode列的不同值并计算结果。这是我的代码：public void getDistinctRecordCount() throws IOException {        Set<String> uniqueSchools = new HashSet<>();        int numOfSchools;        String SchoolCode;    //Filter to only read csv files.    File[] files = Directory.listFiles(new FileExtensionFilter());    for (File f : files) {        CSVParser csvParser;        CSVFormat csvFormat = CSVFormat.DEFAULT.withFirstRecordAsHeader().withIgnoreHeaderCase().withTrim();        reader = Files.newBufferedReader(Paths.get(Directory + "\\" + f.getName() ), StandardCharsets.ISO_8859_1);        csvParser = CSVParser.parse(reader, csvFormat);        for (CSVRecord column : csvParser) {            SchoolCode = column.get("School Code");            uniqueSchools.add(SchoolCode);        }        Logger.info("The list of Schools for " + f.getName() + " are: " + uniqueSchools);        numOfSchools = uniqueSchools.size();        Logger.info("The total count of Schools for " + f.getName() + " are: " + numOfSchools);        Logger.info("-----------------------");    }}这是我的输出：[INFO ] [Logger] - The list of Schools for district1.csv are: [01-0003-002, 01-0003-001][INFO ] [Logger] - The total count of Schools for district1.csv are: 2[INFO ] [Logger] - The list of Schools for district2.csv are: [01-0003-002, 01-0003-001, 01-0018-004, 01-0018-005, 01-0018-002, 01-0018-003, 01-0018-008, 01-0018-006][INFO ] [Logger] - The total count of Schools for district2.csv are: 8问题：从 District1.csv 结果中读取的两个值被附加到 District2.csv 结果中，将我对 District2.csv 的计数减去 2（实际正确值应该是 6）。它是如何附加的？

Answer 1

如果您不需要设置所有学校，您可以uniqueSchools在循环内移动或清除它：

for (File f : files) {

   uniqueSchools.clear();

您还可以将Map<String, String>每个文件保存在学校中或为每个文件创建一个集合，记录计数，然后将所有集合添加到uniqueSchools

Set<String> currentSchools = new HashSet<>();

..

currentSchools.add(SchoolCode);

Logger.info("The list of Schools for " + f.getName() + " are: " + currentSchools);

numOfSchools = currentSchools.size();

Logger.info("The total count of Schools for " + f.getName() + " are: " + numOfSchools);        

uniqueSchools.addAll(currentSchools);

考虑小写（驼峰式）变量的第一个字母，例如更改SchoolCode为schoolCode和Logger到logger