CSV content formatter. - Java File Path IO

Java examples for File Path IO:CSV File

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Description

CSV content formatter.

Demo Code


//package com.java2s;
import java.io.*;

import java.util.Iterator;
import java.util.List;

public class Main {
    private static final char DEFAULT_CSV_SEPARATOR = ';';
    private static final String DEFAULT_LINE_SEPARATOR = "\r\n";

    /**/*w ww.  jav  a2 s  .c  o  m*/
     * CSV content formatter. Convert a two-dimensional List of Objects to a CSV in an InputStream.
     * The value of each Object will be obtained by its toString() method. The fields of each CSV
     * record will be separated by the default CSV field separator, a comma.
     *
     * @param csvList A two-dimensional List of Objects representing the rows and columns of the
     *                CSV.
     * @return The InputStream containing the CSV contents (actually a ByteArrayInputStream).
     */
    public static <T extends Object> InputStream formatCsv(
            List<List<T>> csvList) {
        return formatCsv(csvList, DEFAULT_CSV_SEPARATOR);
    }

    /**
     * CSV content formatter. Convert a two-dimensional List of Objects to a CSV in an InputStream.
     * The value of each Object will be obtained by its toString() method. The fields of each CSV
     * record will be separated by the specified CSV field separator.
     *
     * @param csvList      A two-dimensional List of Objects representing the rows and columns of the
     *                     CSV.
     * @param csvSeparator The CSV field separator to be used.
     * @return The InputStream containing the CSV contents (actually a ByteArrayInputStream).
     */
    public static <T extends Object> InputStream formatCsv(
            List<List<T>> csvList, char csvSeparator) {

        // Prepare.
        StringBuilder csvContent = new StringBuilder();

        // Process records.
        for (List<T> csvRecord : csvList) {
            if (csvRecord != null) {
                csvContent.append(formatCsvRecord(csvRecord, csvSeparator));
            }

            // Add default line separator.
            csvContent.append(DEFAULT_LINE_SEPARATOR);
        }

        return new ByteArrayInputStream(csvContent.toString().getBytes());
    }

    /**
     * CSV record formatter. Convert a List of Objects representing the fields of a CSV record to a
     * String representing the CSV record. The value of each Object will be obtained by its
     * toString() method. The fields of the CSV record will be separated by the specified CSV field
     * separator.
     *
     * @param csvRecord    A List of Objects representing the fields of a CSV reecord.
     * @param csvSeparator The CSV field separator to be used.
     * @return A String representing a CSV record.
     */
    private static <T extends Object> String formatCsvRecord(
            List<T> csvRecord, char csvSeparator) {

        // Prepare.
        StringBuilder fields = new StringBuilder();
        String separator = String.valueOf(csvSeparator);

        // Process fields.
        for (Iterator<T> iter = csvRecord.iterator(); iter.hasNext();) {
            T object = iter.next();

            if (object != null) {
                String field = object.toString().replace("\"", "\"\""); // Escape quotes.

                if (field.contains(separator) || field.contains("\"")) {
                    field = "\"" + field + "\""; // Surround with quotes.
                }

                fields.append(field);
            }

            if (iter.hasNext()) {
                fields.append(separator); // Add field separator.
            }
        }

        return fields.toString();
    }
}

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