org.supercsv.cellprocessor.constraint

Class UniqueHashCode

java.lang.Object

org.supercsv.cellprocessor.CellProcessorAdaptor

org.supercsv.cellprocessor.constraint.UniqueHashCode

All Implemented Interfaces:

CellProcessor

public class UniqueHashCode
extends CellProcessorAdaptor

Ensure that upon processing a CSV file (reading or writing), that values of the column are all unique. Comparison is based upon each elements hashCode() method and lookup takes O(1).

Compared to Unique this processor is much more memory efficient as it only stores the set of encountered hashcodes rather than storing references to all encountered objects. The tradeoff being possible false positives.

Prior to v1.50 this class was named Unique but has been renamed to clarify its inner workings.

Author:

Kasper B. Graversen, Dominique De Vito, James Bassett

Field Summary

Fields inherited from class org.supercsv.cellprocessor.CellProcessorAdaptor

next

Constructor Summary

Constructors

Constructor and Description
UniqueHashCode() Constructs a new UniqueHashCode processor, which ensures that all rows in a column are unique.
UniqueHashCode(CellProcessor next) Constructs a new UniqueHashCode processor, which ensures that all rows in a column are unique, then calls the next processor in the chain.

Method Summary

Modifier and Type	Method and Description
Object	execute(Object value, CsvContext context) This method is invoked by the framework when the processor needs to process data or check constraints.

Methods inherited from class org.supercsv.cellprocessor.CellProcessorAdaptor

toString, validateInputNotNull

Methods inherited from class java.lang.Object

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

Constructor Detail

UniqueHashCode

public UniqueHashCode()

Constructs a new UniqueHashCode processor, which ensures that all rows in a column are unique.

UniqueHashCode

public UniqueHashCode(CellProcessor next)

Constructs a new UniqueHashCode processor, which ensures that all rows in a column are unique, then calls the next processor in the chain.

Parameters:

next - the next processor in the chain

Throws:

NullPointerException - if next is null

Method Detail

execute

public Object execute(Object value,
                      CsvContext context)

This method is invoked by the framework when the processor needs to process data or check constraints.

Parameters:

value - the value to be processed

context - the CSV context

Returns:

the result of cell processor execution

Throws:

SuperCsvCellProcessorException - if value is null

SuperCsvConstraintViolationException - if a non-unique value is encountered