/*
* File: CSVUtility.java
* Authors: Kevin R. Dixon
* Company: Sandia National Laboratories
* Project: Cognitive Foundry
*
* Copyright March 2, 2006, Sandia Corporation. Under the terms of Contract
* DE-AC04-94AL85000, there is a non-exclusive license for use of this work by
* or on behalf of the U.S. Government. Export of this program may require a
* license from the United States Government. See CopyrightHistory.txt for
* complete details.
*
*/
package gov.sandia.cognition.io;
import gov.sandia.cognition.annotation.CodeReview;
import gov.sandia.cognition.annotation.CodeReviewResponse;
import gov.sandia.cognition.annotation.CodeReviews;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;
/**
* The <code>CSVUtility</code> class implements some utility functions for
* dealing with comma-separated value (CSV) file types.
*
* @author Justin Basilico
* @author Kevin R. Dixon
* @since 1.0
*/
@CodeReviews(
reviews={
@CodeReview(
reviewer="Kevin R. Dixon",
date="2006-07-18",
changesNeeded=false,
comments="Minor spacing changes to while statement. Otherwise, looks fine."
),
@CodeReview(
reviewer="Kevin R. Dixon",
date="2008-02-08",
changesNeeded=true,
comments="This class should make the comma a parameter (in the splitCommas() method) so that it can be used on all character-delimited parsing schemes.",
response=@CodeReviewResponse(
respondent="Justin Basilico",
date="2008-02-18",
moreChangesNeeded=false,
comments="Added the split() method"
)
)
}
)
public class CSVUtility
extends java.lang.Object
{
/**
* Returns the next non-empty line from the given BufferedReader as an
* array of the CSV entries. If there is no more data, null is returned.
*
* @param r The BufferedReader to read from.
* @return An array of the comma-separated values on the next line or null
* if the end of the file has been reached.
* @throws IOException If there is an exception in reading from the
* BufferedReader.
*/
public static String[] nextNonEmptyLine(
BufferedReader r)
throws IOException
{
return nextNonEmptyLine(r, ',');
}
/**
* Returns the next non-empty line from the given BufferedReader as an
* array of the CSV entries. If there is no more data, null is returned.
*
* @param r The BufferedReader to read from.
* @param delimiter Delimiter to use.
* @return An array of the comma-separated values on the next line or null
* if the end of the file has been reached.
* @throws IOException If there is an exception in reading from the
* BufferedReader.
*/
public static String[] nextNonEmptyLine(
BufferedReader r,
char delimiter )
throws IOException
{
// Loop over the lines.
String line = null;
while ((line = r.readLine()) != null)
{
line = line.trim();
if (line.length() <= 0)
{
continue;
}
// Split the commas.
String[] entries = CSVUtility.split(line,delimiter);
if (entries != null && entries.length > 0)
{
// Return the line since it had data on it.
return entries;
}
// else - No data on the line.
}
// Nothing found before the end of the reader.
return null;
}
/**
* Splits the given line into the array of comma-separated values. If the
* given line is null, then the value returned is null. If there is no
* data on the line, then an empty array is returned. Otherwise, an array
* containing at least one value is returned.
*
* @param line The line to split on the commas.
* @return The array of comma-separated values from the given line.
*/
public static String[] splitCommas(
final String line)
{
return split(line, ',');
}
/**
* Splits the given line into the array of character-separated values. If
* the given line is null, then the value returned is null. If there is no
* data on the line, then an empty array is returned. Otherwise, an array
* containing at least one value is returned.
*
* @param line The line to split on the given character.
* @param c The character to use to split the line.
* @return The array of comma-separated values from the given line.
*/
public static String[] split(
final String line,
final char c)
{
if (line == null)
{
// Error: Bad line.
return null;
}
// Get the length of the line.
int length = line.length();
if (length <= 0)
{
// The line has no data.
return new String[0];
}
// We build a list of the comma-separated values and at the end turn
// it into an array.
LinkedList<String> list = new LinkedList<String>();
// Keep track of where the current value starts and ends.
int start = 0;
int end = 0;
// Loop over all the commas in the string until we get to the last one.
while ((start < length) &&
((end = line.indexOf(c, start)) >= 0))
{
// Get this value.
String entry = line.substring(start, end);
list.add(entry);
start = end + 1;
}
if (start < length)
{
// Add the last value
String last = line.substring(start);
list.add(last);
}
else
{
// The last thing was a comma.
list.add("");
}
// Convert the list to an array.
return list.toArray(new String[list.size()]);
}
/**
* Reads a CSV file into a list of arrays of string values.
*
* @param fileName The file to read in.
* @return A list of arrays of strings that contain the comma-separated
* values in the given CSV file.
* @throws java.io.IOException If there is an error reading the file.
*/
public static LinkedList<String[]> readFile(
final String fileName )
throws IOException
{
return readFile( fileName, ',' );
}
/**
* Reads a CSV file into a list of arrays of string values.
*
* @param fileName The file to read in.
* @param delimiter Delimiter to use.
* @return A list of arrays of strings that contain the comma-separated
* values in the given CSV file.
* @throws java.io.IOException If there is an error reading the file.
*/
public static LinkedList<String[]> readFile(
final String fileName,
final char delimiter )
throws IOException
{
final LinkedList<String[]> result = new LinkedList<String[]>();
final BufferedReader reader =
new BufferedReader(new FileReader(fileName));
try
{
String[] line = null;
while ((line = nextNonEmptyLine(reader,delimiter)) != null)
{
result.add(line);
}
}
finally
{
reader.close();
}
return result;
}
}