remove Duplicates from List - Java java.util

Java examples for java.util:List Operation

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Description

remove Duplicates from List

Demo Code

/*/*from   ww  w  .j  a v a  2 s .co m*/
 * Copyright 2001-2008 Aqris Software AS. All rights reserved.
 * 
 * This program is dual-licensed under both the Common Development
 * and Distribution License ("CDDL") and the GNU General Public
 * License ("GPL"). You may elect to use one or the other of these
 * licenses.
 */
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

public class Main {
  public static void main(String[] argv) {
    List list = java.util.Arrays.asList("asdf", "java2s.com");
    removeDuplicates(list);
  }

  public static final void removeDuplicates(List list) {
    List duplicatesToRemove = new ArrayList();

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

      for (int k = i + 1; k < list.size(); k++) {
        if (i != k) {
          final Object second = list.get(k);

          if (first.equals(second)) {
            addNew(duplicatesToRemove, second);
          }
        }
      }
    }

    for (int i = 0; i < duplicatesToRemove.size(); i++) {
      final Object duplicate = duplicatesToRemove.get(i);
      list.remove(duplicate);
    }
  }

  public static final void removeDuplicates(List list, Comparator comparator) {
    List duplicatesToRemove = new ArrayList();

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

      for (int k = i + 1; k < list.size(); k++) {
        if (i != k) {
          final Object second = list.get(k);

          if (comparator.compare(first, second) == 0) {
            duplicatesToRemove.add(second);
            // CollectionUtil.addNew(duplicatesToRemove, second, comparator);
          }
        }
      }
    }

    list.removeAll(duplicatesToRemove);

  }

  public static final List addNew(List list, Object object) {
    if (!list.contains(object)) {
      list.add(object);
    }

    return list;
  }

}

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