Using Apache Commons CSV for parsing, but doesn't ignore missing column and throws exception.
with this sample data:
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]. I need it returns null, optional or default value. Is there any option? I know it is possible with record.toMap().get(DataColumns.surname.name()) but its performance will not be good:
...
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.
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()).
Then, you can use the resulting variable inside the loop by calling headerNames.contains(columnName) to check whether the column exists or not.
Plese, see: https://javadoc.io/doc/org.apache.commons/commons-csv/latest/org/apache/commons/csv/CSVRecord.html