[英]Apache Commons CSV doesn't ignore missing column
Using Apache Commons CSV for parsing, but doesn't ignore missing column and throws exception.使用 Apache Commons CSV 进行解析,但不会忽略缺失的列并抛出异常。
with this sample data:使用此示例数据:
name age
Ali 35
John 25
Vahid 75
Below code record.get(DataColumns.surname)
throws java.lang.IllegalArgumentException: Mapping for surname not found, expected one of [name, surname, age]
.下面的代码
record.get(DataColumns.surname)
抛出java.lang.IllegalArgumentException: Mapping for surname not found, expected one of [name, surname, age]
。 I need it returns null, optional or default value.我需要它返回空值、可选值或默认值。 Is there any option?
有什么选择吗? I know it is possible with
record.toMap().get(DataColumns.surname.name())
but its performance will not be good:我知道
record.toMap().get(DataColumns.surname.name())
是可能的,但它的性能不会很好:
...
enum DataColumns { name, surname, age }
...
Reader in = new BufferedReader(new FileReader(fileName));
try (CSVParser records = CSVFormat.TDF
.withDelimiter(' ')
.withIgnoreSurroundingSpaces()
.withAllowDuplicateHeaderNames(false)
.withIgnoreHeaderCase()
.withTrim()
.withHeader(DataColumns.class)
.withFirstRecordAsHeader()
.withSkipHeaderRecord()
.withAllowMissingColumnNames(false)
.withIgnoreEmptyLines()
.parse(in)) {
for (CSVRecord record : records) {
String name = record.get(DataColumns.name);
String surname = record.get(DataColumns.surname);
Short age = Short.valueOf(record.get(DataColumns.age));
}
}
...
You might try using record.isMapped(columnName)
to check if the column exists, recording into a variable so you don't have to check again every line.您可以尝试使用
record.isMapped(columnName)
来检查该列是否存在,记录到一个变量中,这样您就不必再次检查每一行。
Another option would be to use records.getHeaderNames()
and store it into a variable once, before the loop, maybe even using a Set<String>
for an extra kick of existance checking performance: Set<String> headerNames = new HashSet<>(records.getHeaderNames())
.另一种选择是使用
records.getHeaderNames()
并在循环之前将其存储到变量中一次,甚至可能使用Set<String>
来提高存在性检查性能: Set<String> headerNames = new HashSet<>(records.getHeaderNames())
。
Then, you can use the resulting variable inside the loop by calling headerNames.contains(columnName)
to check whether the column exists or not.然后,您可以通过调用
headerNames.contains(columnName)
在循环内使用结果变量来检查该列是否存在。
Plese, see: https://javadoc.io/doc/org.apache.commons/commons-csv/latest/org/apache/commons/csv/CSVRecord.html请参阅: https ://javadoc.io/doc/org.apache.commons/commons-csv/latest/org/apache/commons/csv/CSVRecord.html
There is method: record.get(String) while you gave enum instead.有方法:record.get(String) 而你给了枚举。
Try record.get(DataColumns.name.name())试试 record.get(DataColumns.name.name())
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