Wrap multi-line strings (and get the individual lines) : BreakIterator « I18N « Java Tutorial

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3. BreakIterator

/*
 * $Id: Utilities.java,v 1.11 2008/10/14 22:31:46 rah003 Exp $
 *
 * Copyright 2006 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * 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 St, Fifth Floor, Boston, MA  02110-1301  USA
 */

import java.text.BreakIterator;
import java.util.StringTokenizer;

/**
 * Contribution from NetBeans: Issue #319-swingx.
 * 
 * 
 * PENDING: need to reconcile with OS, JVM... added as-is because needed the
 * shortcut handling to fix #
 * 
 * @author apple
 */
public class Utils {

  /**
   * Wrap multi-line strings (and get the individual lines).
   * 
   * @param original
   *          the original string to wrap
   * @param width
   *          the maximum width of lines
   * @param breakIterator
   *          breaks original to chars, words, sentences, depending on what
   *          instance you provide.
   * @param removeNewLines
   *          if <code>true</code>, any newlines in the original string are
   *          ignored
   * @return the lines after wrapping
   */
  public static String[] wrapStringToArray(String original, int width, BreakIterator breakIterator,
      boolean removeNewLines) {
    if (original.length() == 0) {
      return new String[] { original };
    }

    String[] workingSet;

    // substitute original newlines with spaces,
    // remove newlines from head and tail
    if (removeNewLines) {
      original = trimString(original);
      original = original.replace('\n', ' ');
      workingSet = new String[] { original };
    } else {
      StringTokenizer tokens = new StringTokenizer(original, "\n"); // NOI18N
      int len = tokens.countTokens();
      workingSet = new String[len];

      for (int i = 0; i < len; i++) {
        workingSet[i] = tokens.nextToken();
      }
    }

    if (width < 1) {
      width = 1;
    }

    if (original.length() <= width) {
      return workingSet;
    }

    widthcheck: {
      boolean ok = true;

      for (int i = 0; i < workingSet.length; i++) {
        ok = ok && (workingSet[i].length() < width);

        if (!ok) {
          break widthcheck;
        }
      }

      return workingSet;
    }

    java.util.ArrayList<String> lines = new java.util.ArrayList<String>();

    int lineStart = 0; // the position of start of currently processed line in
                        // the original string

    for (int i = 0; i < workingSet.length; i++) {
      if (workingSet[i].length() < width) {
        lines.add(workingSet[i]);
      } else {
        breakIterator.setText(workingSet[i]);

        int nextStart = breakIterator.next();
        int prevStart = 0;

        do {
          while (((nextStart - lineStart) < width) && (nextStart != BreakIterator.DONE)) {
            prevStart = nextStart;
            nextStart = breakIterator.next();
          }

          if (nextStart == BreakIterator.DONE) {
            nextStart = prevStart = workingSet[i].length();
          }

          if (prevStart == 0) {
            prevStart = nextStart;
          }

          lines.add(workingSet[i].substring(lineStart, prevStart));

          lineStart = prevStart;
          prevStart = 0;
        } while (lineStart < workingSet[i].length());

        lineStart = 0;
      }
    }

    String[] s = new String[lines.size()];

    return (String[]) lines.toArray(s);
  }

  private static String trimString(String s) {
    int idx = 0;
    char c;
    final int slen = s.length();

    if (slen == 0) {
      return s;
    }

    do {
      c = s.charAt(idx++);
    } while (((c == '\n') || (c == '\r')) && (idx < slen));

    s = s.substring(--idx);
    idx = s.length() - 1;

    if (idx < 0) {
      return s;
    }

    do {
      c = s.charAt(idx--);
    } while (((c == '\n') || (c == '\r')) && (idx >= 0));

    return s.substring(0, idx + 2);
  }
}