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jfreechart example source code file (CSV.java)

This example jfreechart source code file (CSV.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

bufferedreader, categorydataset, comparable, comparable, csv, defaultcategorydataset, defaultcategorydataset, double, io, ioexception, list, list, string, string, util

The jfreechart CSV.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * --------
 * CSV.java
 * --------
 * (C) Copyright 2003-2008, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes
 * -------
 * 24-Nov-2003 : Version 1 (DG);
 *
 */

package org.jfree.data.io;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.util.List;

import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * A utility class for reading {@link CategoryDataset} data from a CSV file.
 * This initial version is very basic, and won't handle errors in the data
 * file very gracefully.
 */
public class CSV {

    /** The field delimiter. */
    private char fieldDelimiter;

    /** The text delimiter. */
    private char textDelimiter;

    /**
     * Creates a new CSV reader where the field delimiter is a comma, and the
     * text delimiter is a double-quote.
     */
    public CSV() {
        this(',', '"');
    }

    /**
     * Creates a new reader with the specified field and text delimiters.
     *
     * @param fieldDelimiter  the field delimiter (usually a comma, semi-colon,
     *                        colon, tab or space).
     * @param textDelimiter  the text delimiter (usually a single or double
     *                       quote).
     */
    public CSV(char fieldDelimiter, char textDelimiter) {
        this.fieldDelimiter = fieldDelimiter;
        this.textDelimiter = textDelimiter;
    }

    /**
     * Reads a {@link CategoryDataset} from a CSV file or input source.
     *
     * @param in  the input source.
     *
     * @return A category dataset.
     *
     * @throws IOException if there is an I/O problem.
     */
    public CategoryDataset readCategoryDataset(Reader in) throws IOException {

        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        BufferedReader reader = new BufferedReader(in);
        List columnKeys = null;
        int lineIndex = 0;
        String line = reader.readLine();
        while (line != null) {
            if (lineIndex == 0) {  // first line contains column keys
                columnKeys = extractColumnKeys(line);
            }
            else {  // remaining lines contain a row key and data values
                extractRowKeyAndData(line, dataset, columnKeys);
            }
            line = reader.readLine();
            lineIndex++;
        }
        return dataset;

    }

    /**
     * Extracts the column keys from a string.
     *
     * @param line  a line from the input file.
     *
     * @return A list of column keys.
     */
    private List extractColumnKeys(String line) {
        List keys = new java.util.ArrayList();
        int fieldIndex = 0;
        int start = 0;
        for (int i = 0; i < line.length(); i++) {
            if (line.charAt(i) == this.fieldDelimiter) {
                if (fieldIndex > 0) {  // first field is ignored, since
                                       // column 0 is for row keys
                    String key = line.substring(start, i);
                    keys.add(removeStringDelimiters(key));
                }
                start = i + 1;
                fieldIndex++;
            }
        }
        String key = line.substring(start, line.length());
        keys.add(removeStringDelimiters(key));
        return keys;
    }

    /**
     * Extracts the row key and data for a single line from the input source.
     *
     * @param line  the line from the input source.
     * @param dataset  the dataset to be populated.
     * @param columnKeys  the column keys.
     */
    private void extractRowKeyAndData(String line,
                                      DefaultCategoryDataset dataset,
                                      List columnKeys) {
        Comparable rowKey = null;
        int fieldIndex = 0;
        int start = 0;
        for (int i = 0; i < line.length(); i++) {
            if (line.charAt(i) == this.fieldDelimiter) {
                if (fieldIndex == 0) {  // first field contains the row key
                    String key = line.substring(start, i);
                    rowKey = removeStringDelimiters(key);
                }
                else {  // remaining fields contain values
                    Double value = Double.valueOf(
                        removeStringDelimiters(line.substring(start, i))
                    );
                    dataset.addValue(
                        value, rowKey,
                        (Comparable) columnKeys.get(fieldIndex - 1)
                    );
                }
                start = i + 1;
                fieldIndex++;
            }
        }
        Double value = Double.valueOf(
            removeStringDelimiters(line.substring(start, line.length()))
        );
        dataset.addValue(
            value, rowKey, (Comparable) columnKeys.get(fieldIndex - 1)
        );
    }

    /**
     * Removes the string delimiters from a key (as well as any white space
     * outside the delimiters).
     *
     * @param key  the key (including delimiters).
     *
     * @return The key without delimiters.
     */
    private String removeStringDelimiters(String key) {
        String k = key.trim();
        if (k.charAt(0) == this.textDelimiter) {
            k = k.substring(1);
        }
        if (k.charAt(k.length() - 1) == this.textDelimiter) {
            k = k.substring(0, k.length() - 1);
        }
        return k;
    }

}

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