Java String Whitespace Collapse collapseWhiteSpace(String string)

Description

After the processing implied by replace, contiguous sequences of #x20's are collapsed to a single #x20, and leading and trailing #x20's are removed.

License

Open Source License

Parameter

Parameter	Description
string	a parameter

Return

the string with collapsed whitespace, null if string is null.

Declaration

public static String collapseWhiteSpace(String string)

Method Source Code

//package com.java2s;
/*/*w  ww  .j a va2  s  .  co m*/
 * sulky-modules - several general-purpose modules.
 * Copyright (C) 2007-2008 Joern Huxhorn
 * 
 * This program 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 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */

public class Main {
    private static final char TAB = 0x09;
    private static final char LINE_FEED = 0x0A;
    private static final char CARRIAGE_RETURN = 0x0D;
    private static final char SPACE = 0x20;

    /**
     * After the processing implied by replace, contiguous sequences of #x20's
     * are collapsed to a single #x20, and leading and trailing #x20's are
     * removed.
     * 
     * @param string
     * @return the string with collapsed whitespace, null if string is null.
     * @see #replaceWhiteSpace(String)
     */
    public static String collapseWhiteSpace(String string) {
        if (string == null) {
            return null;
        }
        String replaced = replaceWhiteSpace(string);
        char[] chars = replaced.toCharArray();
        StringBuffer result = new StringBuffer(replaced.length());
        boolean needSpace = false;
        for (char c : chars) {
            if (c == SPACE) {
                if (result.length() != 0) {
                    // we are not at the start anymore
                    needSpace = true;
                }
            } else {
                if (needSpace) {
                    needSpace = false;
                    result.append(SPACE);
                }
                result.append(c);
            }
        }
        return result.toString();
    }

    /**
     * All occurrences of #x9 (tab), #xA (line feed) and #xD (carriage return)
     * are replaced with #x20 (space)
     * 
     * @param string
     * @return the string with replaced whitespace, null if string is null.
     */
    public static String replaceWhiteSpace(String string) {
        if (string == null) {
            return null;
        }
        StringBuffer result = new StringBuffer(string);
        for (int i = 0; i < result.length(); i++) {
            char c = result.charAt(i);
            if (c == TAB || c == CARRIAGE_RETURN || c == LINE_FEED) {
                result.setCharAt(i, SPACE);
            }
        }
        return result.toString();
    }
}