Convenience method to convert a CSV string list to a set. - Java File Path IO

Description

Convenience method to convert a CSV string list to a set.

Demo Code

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import java.util.Scanner;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeSet;

public class Main{
    public static void main(String[] argv) throws Exception{
        String str = "java2s.com";
        System.out.println(commaDelimitedListToSet(str));
    }/*from w  w  w.  j  a v  a  2s.  co  m*/
    /**
     * Convenience method to convert a CSV string list to a set. Note that this will suppress duplicates.
     *
     * @param str
     *            the input String
     * @return a Set of String entries in the list
     */
    public static Set<String> commaDelimitedListToSet(final String str) {

        final Set<String> set = new TreeSet<String>();
        final String[] tokens = commaDelimitedListToStringArray(str);
        for (final String token : tokens) {
            set.add(token);
        }
        return set;
    }
    /**
     * Convert a CSV list into an array of Strings.
     *
     * @param str
     *            the input String
     * @return an array of Strings, or the empty array in case of empty input
     */
    public static String[] commaDelimitedListToStringArray(final String str) {

        return delimitedListToStringArray(str, ",");
    }
    /**
     * Take a String which is a delimited list and convert it to a String array. <p>A single delimiter can
     * consists of more than one character: It will still be considered as single delimiter string, rather
     * than as bunch of potential delimiter characters - in contrast to <code>tokenizeToStringArray</code>.
     *
     * @param str
     *            the input String
     * @param delimiter
     *            the delimiter between elements (this is a single delimiter, rather than a bunch individual
     *            delimiter characters)
     * @return an array of the tokens in the list
     * @see #tokenizeToStringArray
     */
    public static String[] delimitedListToStringArray(final String str,
            final String delimiter) {

        return delimitedListToStringArray(str, delimiter, null);
    }
    /**
     * Take a String which is a delimited list and convert it to a String array. <p>A single delimiter can
     * consists of more than one character: It will still be considered as single delimiter string, rather
     * than as bunch of potential delimiter characters - in contrast to <code>tokenizeToStringArray</code>.
     *
     * @param str
     *            the input String
     * @param delimiter
     *            the delimiter between elements (this is a single delimiter, rather than a bunch individual
     *            delimiter characters)
     * @param charsToDelete
     *            a set of characters to delete. Useful for deleting unwanted line breaks: e.g. "\r\n\f" will
     *            delete all new lines and line feeds in a String.
     * @return an array of the tokens in the list
     * @see #tokenizeToStringArray
     */
    public static String[] delimitedListToStringArray(final String str,
            final String delimiter, final String charsToDelete) {

        if (str == null)
            return new String[0];
        if (delimiter == null)
            return new String[] { str };
        final List<String> result = new ArrayList<String>();
        if ("".equals(delimiter)) {
            for (int i = 0; i < str.length(); i++) {
                result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
            }
        } else {
            int pos = 0;
            int delPos;
            while ((delPos = str.indexOf(delimiter, pos)) != -1) {
                result.add(deleteAny(str.substring(pos, delPos),
                        charsToDelete));
                pos = delPos + delimiter.length();
            }
            if ((str.length() > 0) && (pos <= str.length())) {
                // Add rest of String, but not in case of empty input.
                result.add(deleteAny(str.substring(pos), charsToDelete));
            }
        }
        return toStringArray(result);
    }
    /**
     * Delete any character in a given String.
     *
     * @param inString
     *            the original String
     * @param charsToDelete
     *            a set of characters to delete. E.g. "az\n" will delete 'a's, 'z's and new lines.
     * @return the resulting String
     */
    public static String deleteAny(final String inString,
            final String charsToDelete) {

        if (!hasLength(inString) || !hasLength(charsToDelete))
            return inString;
        final StringBuilder sb = new StringBuilder();
        for (int i = 0; i < inString.length(); i++) {
            final char c = inString.charAt(i);
            if (charsToDelete.indexOf(c) == -1) {
                sb.append(c);
            }
        }
        return sb.toString();
    }
    /**
     * Copy the given Collection into a String array. The Collection must contain String elements only.
     *
     * @param collection
     *            the Collection to copy
     * @return the String array (<code>null</code> if the passed-in Collection was <code>null</code>)
     */
    public static String[] toStringArray(final Collection<String> collection) {

        if (collection == null)
            return null;
        return collection.toArray(new String[collection.size()]);
    }
    /**
     * Copy the given Enumeration into a String array. The Enumeration must contain String elements only.
     *
     * @param enumeration
     *            the Enumeration to copy
     * @return the String array (<code>null</code> if the passed-in Enumeration was <code>null</code>)
     */
    public static String[] toStringArray(
            final Enumeration<String> enumeration) {

        if (enumeration == null)
            return null;
        final List<String> list = Collections.list(enumeration);
        return list.toArray(new String[list.size()]);
    }
}

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