ListUtil.java :  » Portal » liferay-portal-4.4.2 » com » liferay » util » Java Open Source

/**
 * Copyright (c) 2000-2008 Liferay, Inc. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.liferay.util;

import com.liferay.portal.kernel.util.StringMaker;
import com.liferay.portal.kernel.util.StringPool;
import com.liferay.portal.kernel.util.StringUtil;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

/**
 * <a href="ListUtil.java.html"><b><i>View Source</i></b></a>
 *
 * @author Brian Wing Shun Chan
 *
 */
public class ListUtil {

  public static List copy(List master) {
    if (master == null) {
      return null;
    }

    List copy = new ArrayList(master.size());

    copy(master, copy);

    return copy;
  }

  public static void copy(List master, List copy) {
    if ((master == null) || (copy == null)) {
      return;
    }

    copy.clear();

    Iterator itr = master.iterator();

    while (itr.hasNext()) {
      Object obj = itr.next();

      copy.add(obj);
    }
  }

  public static void distinct(List list) {
    distinct(list, null);
  }

  public static void distinct(List list, Comparator comparator) {
    if ((list == null) || (list.size() == 0)) {
      return;
    }

    Set set = null;

    if (comparator == null) {
      set = new TreeSet();
    }
    else {
      set = new TreeSet(comparator);
    }

    Iterator itr = list.iterator();

    while (itr.hasNext()) {
      Object obj = itr.next();

      if (set.contains(obj)) {
        itr.remove();
      }
      else {
        set.add(obj);
      }
    }
  }

  public static List fromArray(Object[] array) {
    if ((array == null) || (array.length == 0)) {
      return new ArrayList();
    }

    List list = new ArrayList(array.length);

    for (int i = 0; i < array.length; i++) {
      list.add(array[i]);
    }

    return list;
  }

  public static List fromCollection(Collection c) {
    if ((c != null) && (c instanceof List)) {
      return (List)c;
    }

    if ((c == null) || (c.size() == 0)) {
      return new ArrayList();
    }

    List list = new ArrayList(c.size());

    Iterator itr = c.iterator();

    while (itr.hasNext()) {
      list.add(itr.next());
    }

    return list;
  }

  public static List fromEnumeration(Enumeration enu) {
    List list = new ArrayList();

    while (enu.hasMoreElements()) {
      Object obj = enu.nextElement();

      list.add(obj);
    }

    return list;
  }

  public static List fromFile(String fileName) throws IOException {
    return fromFile(new File(fileName));
  }

  public static List fromFile(File file) throws IOException {
    List list = new ArrayList();

    BufferedReader br = new BufferedReader(new FileReader(file));

    String s = StringPool.BLANK;

    while ((s = br.readLine()) != null) {
      list.add(s);
    }

    br.close();

    return list;
  }

  public static List fromString(String s) {
    return fromArray(StringUtil.split(s, StringPool.NEW_LINE));
  }

  public static List subList(List list, int begin, int end) {
    List newList = new ArrayList();

    int normalizedSize = list.size() - 1;

    if ((begin < 0) || (begin > normalizedSize) || (end < 0) ||
      (begin > end)) {

      return newList;
    }

    for (int i = begin; i < end && i <= normalizedSize; i++) {
      newList.add(list.get(i));
    }

    return newList;
  }

  public static String toString(List list, String param) {
    return toString(list, param, StringPool.COMMA);
  }

  public static String toString(List list, String param, String delimiter) {
    StringMaker sm = new StringMaker();

    for (int i = 0; i < list.size(); i++) {
      Object bean = list.get(i);

      Object value = BeanUtil.getObject(bean, param);

      if (value == null) {
        value = StringPool.BLANK;
      }

      sm.append(value.toString());

      if ((i + 1) != list.size()) {
        sm.append(delimiter);
      }
    }

    return sm.toString();
  }

}