Java String Split by Length splitByWholeSeparatorWorker(final String str, final String separator, final int max, final boolean preserveAllTokens)

Description

Performs the logic for the splitByWholeSeparatorPreserveAllTokens methods.

License

Apache License

Parameter

Parameter	Description
str	the String to parse, may be null
separator	String containing the String to be used as a delimiter, null splits on whitespace
max	the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
preserveAllTokens	if true , adjacent separators are treated as empty token separators; if false , adjacent separators are treated as one separator.

Return

an array of parsed Strings, null if null String input

Declaration

private static String[] splitByWholeSeparatorWorker(final String str, final String separator, final int max,
        final boolean preserveAllTokens) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.util.*;

public class Main {
    /**/*from ww  w .  j  a  va  2s . c om*/
     * The empty String <code>""</code>.
     *
     * @since 2.0
     */
    public static final String EMPTY = "";
    /**
     * An empty immutable {@code String} array.
     */
    public static final String[] EMPTY_STRING_ARRAY = new String[0];

    /**
     * Performs the logic for the {@code splitByWholeSeparatorPreserveAllTokens}
     * methods.
     *
     * @param str               the String to parse, may be {@code null}
     * @param separator         String containing the String to be used as a delimiter,
     *                          {@code null} splits on whitespace
     * @param max               the maximum number of elements to include in the returned
     *                          array. A zero or negative value implies no limit.
     * @param preserveAllTokens if {@code true}, adjacent separators are treated as empty
     *                          token separators; if {@code false}, adjacent separators are
     *                          treated as one separator.
     * @return an array of parsed Strings, {@code null} if null String input
     * @since 2.4
     */
    private static String[] splitByWholeSeparatorWorker(final String str, final String separator, final int max,
            final boolean preserveAllTokens) {
        if (str == null) {
            return null;
        }

        final int len = str.length();

        if (len == 0) {
            return EMPTY_STRING_ARRAY;
        }

        if (separator == null || EMPTY.equals(separator)) {
            // Split on whitespace.
            return splitWorker(str, null, max, preserveAllTokens);
        }

        final int separatorLength = separator.length();

        final ArrayList<String> substrings = new ArrayList<String>();
        int numberOfSubstrings = 0;
        int beg = 0;
        int end = 0;
        while (end < len) {
            end = str.indexOf(separator, beg);

            if (end > -1) {
                if (end > beg) {
                    numberOfSubstrings += 1;

                    if (numberOfSubstrings == max) {
                        end = len;
                        substrings.add(str.substring(beg));
                    } else {
                        // The following is OK, because String.substring( beg,
                        // end ) excludes
                        // the character at the position 'end'.
                        substrings.add(str.substring(beg, end));

                        // Set the starting point for the next search.
                        // The following is equivalent to beg = end +
                        // (separatorLength - 1) + 1,
                        // which is the right calculation:
                        beg = end + separatorLength;
                    }
                } else {
                    // We found a consecutive occurrence of the separator, so
                    // skip it.
                    if (preserveAllTokens) {
                        numberOfSubstrings += 1;
                        if (numberOfSubstrings == max) {
                            end = len;
                            substrings.add(str.substring(beg));
                        } else {
                            substrings.add(EMPTY);
                        }
                    }
                    beg = end + separatorLength;
                }
            } else {
                // String.substring( beg ) goes from 'beg' to the end of the
                // String.
                substrings.add(str.substring(beg));
                end = len;
            }
        }

        return substrings.toArray(new String[substrings.size()]);
    }

    /**
     * Performs the logic for the {@code split} and
     * {@code splitPreserveAllTokens} methods that do not return a maximum array
     * length.
     *
     * @param str               the String to parse, may be {@code null}
     * @param separatorChar     the separate character
     * @param preserveAllTokens if {@code true}, adjacent separators are treated as empty
     *                          token separators; if {@code false}, adjacent separators are
     *                          treated as one separator.
     * @return an array of parsed Strings, {@code null} if null String input
     */
    private static String[] splitWorker(final String str, final char separatorChar,
            final boolean preserveAllTokens) {
        // Performance tuned for 2.0 (JDK1.4)

        if (str == null) {
            return null;
        }
        final int len = str.length();
        if (len == 0) {
            return EMPTY_STRING_ARRAY;
        }
        final List<String> list = new ArrayList<String>();
        int i = 0, start = 0;
        boolean match = false;
        boolean lastMatch = false;
        while (i < len) {
            if (str.charAt(i) == separatorChar) {
                if (match || preserveAllTokens) {
                    list.add(str.substring(start, i));
                    match = false;
                    lastMatch = true;
                }
                start = ++i;
                continue;
            }
            lastMatch = false;
            match = true;
            i++;
        }
        if (match || preserveAllTokens && lastMatch) {
            list.add(str.substring(start, i));
        }
        return list.toArray(new String[list.size()]);
    }

    /**
     * Performs the logic for the {@code split} and
     * {@code splitPreserveAllTokens} methods that return a maximum array
     * length.
     *
     * @param str               the String to parse, may be {@code null}
     * @param separatorChars    the separate character
     * @param max               the maximum number of elements to include in the array. A zero
     *                          or negative value implies no limit.
     * @param preserveAllTokens if {@code true}, adjacent separators are treated as empty
     *                          token separators; if {@code false}, adjacent separators are
     *                          treated as one separator.
     * @return an array of parsed Strings, {@code null} if null String input
     */
    private static String[] splitWorker(final String str, final String separatorChars, final int max,
            final boolean preserveAllTokens) {
        // Performance tuned for 2.0 (JDK1.4)
        // Direct code is quicker than StringTokenizer.
        // Also, StringTokenizer uses isSpace() not isWhitespace()

        if (str == null) {
            return null;
        }
        final int len = str.length();
        if (len == 0) {
            return EMPTY_STRING_ARRAY;
        }
        final List<String> list = new ArrayList<String>();
        int sizePlus1 = 1;
        int i = 0, start = 0;
        boolean match = false;
        boolean lastMatch = false;
        if (separatorChars == null) {
            // Null separator means use whitespace
            while (i < len) {
                if (Character.isWhitespace(str.charAt(i))) {
                    if (match || preserveAllTokens) {
                        lastMatch = true;
                        if (sizePlus1++ == max) {
                            i = len;
                            lastMatch = false;
                        }
                        list.add(str.substring(start, i));
                        match = false;
                    }
                    start = ++i;
                    continue;
                }
                lastMatch = false;
                match = true;
                i++;
            }
        } else if (separatorChars.length() == 1) {
            // Optimise 1 character case
            final char sep = separatorChars.charAt(0);
            while (i < len) {
                if (str.charAt(i) == sep) {
                    if (match || preserveAllTokens) {
                        lastMatch = true;
                        if (sizePlus1++ == max) {
                            i = len;
                            lastMatch = false;
                        }
                        list.add(str.substring(start, i));
                        match = false;
                    }
                    start = ++i;
                    continue;
                }
                lastMatch = false;
                match = true;
                i++;
            }
        } else {
            // standard case
            while (i < len) {
                if (separatorChars.indexOf(str.charAt(i)) >= 0) {
                    if (match || preserveAllTokens) {
                        lastMatch = true;
                        if (sizePlus1++ == max) {
                            i = len;
                            lastMatch = false;
                        }
                        list.add(str.substring(start, i));
                        match = false;
                    }
                    start = ++i;
                    continue;
                }
                lastMatch = false;
                match = true;
                i++;
            }
        }
        if (match || preserveAllTokens && lastMatch) {
            list.add(str.substring(start, i));
        }
        return list.toArray(new String[list.size()]);
    }

    public static String[] toArray(List<String> array) {
        return array.toArray(new String[] {});
    }
}

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