Class CsvCallbackHandler<T>

java.lang.Object
de.siegmar.fastcsv.reader.CsvCallbackHandler<T>
Type Parameters:
T - the type of the record that is built from the CSV data
Direct Known Subclasses:
AbstractBaseCsvCallbackHandler, AbstractInternalCsvCallbackHandler
public abstract class CsvCallbackHandler<T> extends Object

This class defines the methods that are called during the CSV reading process.

Implementations highly affect the behavior of the CsvReader. With great power comes great responsibility. Don't mess up the CSV reading process!

Even if you need custom handling, you typically don't need to extend this class directly. Check out AbstractBaseCsvCallbackHandler first.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    CsvCallbackHandler()
    Default constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected abstract void
    addField(char[] buf, int offset, int len, boolean quoted)
    Called for each field in the record.
    protected abstract void
    beginRecord(long startingLineNumber)
    Called at the beginning of each record.
    protected abstract T
    buildRecord()
    Called at the end of each CSV record to build the actual record representation.
    protected abstract int
    getFieldCount()
    Returns the number of fields in the record.
    protected abstract RecordType
    getRecordType()
    Returns the type of the record that is built from the CSV data.
    protected abstract void
    setComment(char[] buf, int offset, int len)
    Called for each comment line.
    protected abstract void
    setEmpty()
    Called for each empty line.
    protected void
    terminate()
    Called at the end of the CSV reading process.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • CsvCallbackHandler

      protected CsvCallbackHandler()
      Default constructor.

  • Method Details

    • getRecordType

      protected abstract RecordType getRecordType()

      Returns the type of the record that is built from the CSV data.

      The CsvReader will skip

      Returns:
      the type of the record that is built from the CSV data

    • getFieldCount

      protected abstract int getFieldCount()

      Returns the number of fields in the record.

      The CsvReader will verify that the number of fields in each record matches the number of fields in the first record unless CsvReader.CsvReaderBuilder.allowExtraFields(boolean) or CsvReader.CsvReaderBuilder.allowMissingFields(boolean) are set to true.

      Returns:
      the number of fields in the record

    • beginRecord

      protected abstract void beginRecord(long startingLineNumber)

      Called at the beginning of each record.

      The startingLineNumber is the line number where the record starts (starting with 1).

      Parameters:
      startingLineNumber - the line number where the record starts (starting with 1)

    • addField

      protected abstract void addField(char[] buf, int offset, int len, boolean quoted)

      Called for each field in the record.

      A record can either be a comment or a regular record. If this method is called, the record is a regular record and cannot be a comment.

      The quoted parameter indicates whether the field was quoted. It is for informational purposes only. Any potential escape characters are already removed and the offset points to the first character after the opening quote and the len does not include the closing quote. Hence, a quoted field can be processed in the same way as an unquoted field. Some implementations need the information whether a field was quoted, e.g., for differentiating between null and empty fields (foo,,bar vs. foo,"",bar).

      The buf parameter is the internal buffer that contains the field value (among other data). Do not attempt to modify the buffer or store a reference to it. The buffer is reused for performance reasons.

      Parameters:
      buf - the internal buffer that contains the field value (among other data)
      offset - the offset of the field value in the buffer
      len - the length of the field value
      quoted - true if the field was quoted

    • setComment

      protected abstract void setComment(char[] buf, int offset, int len)

      Called for each comment line.

      Note that the comment character is not included in the value.

      This method is not called if CsvReader.CsvReaderBuilder.commentStrategy(CommentStrategy) is set to CommentStrategy.NONE.

      There can only be one invocation of this method per record. A record can either be a comment or a regular record. If this method is called, the record is a comment and cannot be a regular record.

      The buf parameter is the internal buffer that contains the field value (among other data). Do not attempt to modify the buffer or store a reference to it. The buffer is reused for performance reasons.

      Parameters:
      buf - the internal buffer that contains the field value (among other data)
      offset - the offset of the field value in the buffer
      len - the length of the field value

    • setEmpty

      protected abstract void setEmpty()
      Called for each empty line.

    • buildRecord

      protected abstract T buildRecord()
      Called at the end of each CSV record to build the actual record representation.
      Returns:
      the record or null if the record should be ignored/skipped as it is consumed by the callback handler.

    • terminate

      protected void terminate()
      Called at the end of the CSV reading process.