list数据去重复

package list.test;

import java.util.*;

/**
 * @author jia
 * @create 
 */
public class ListTest {
    final static int _capacity = 100000;
    final static Random rand = new Random(System.currentTimeMillis() + _capacity);
    static List<String> list = new ArrayList<String>();
    static List<String> newList = new ArrayList<String>();

    public static void main(String[] args) {
        long ts = System.currentTimeMillis();
        int modVal = _capacity / 3;
        for (int i = 0; i < _capacity; i++) {
            rand.setSeed(i);
            list.add(Integer.toString(Math.abs(rand.nextInt() % modVal)));
        }
        ts = System.currentTimeMillis() - ts;
        System.out.println("生成十万条数据时间：" + ts);

        test1();
        test2();
    }

    public static void test1() {
        newList.clear();
        int repetition = 0;
        long ts = System.currentTimeMillis();
        for (String temp : list) {
            if (!newList.contains(temp)) {
                newList.add(temp);
            } else {
                repetition++;
            }
        }
        ts = System.currentTimeMillis() - ts;
        System.out.println("十万条数据test1方法耗时：" + ts);
        System.out.println("重复的数据条数：" + repetition);
        System.out.println("新数组的大小：" + newList.size());
    }

    public static void test2() {

        Long ts = System.currentTimeMillis();
        int repetition = 0;
        newList.clear();
        Collections.sort(list, new Comparator<String>() {
            // 降序排列
            public int compare(String o1, String o2) {
                return Integer.valueOf(o2) - Integer.valueOf(o1);
            }
        });

        String str = list.get(0);
        for (int i = 1; i < list.size(); i++) {
            if (str.equals(list.get(i))) {
                repetition++;
                continue;
            } else {
                newList.add(str);
                str = list.get(i);
            }
        }
        newList.add(str);
        ts = System.currentTimeMillis() - ts;
        System.out.println("十万条数据test2方法耗时：" + ts);
        System.out.println("重复的数据条数：" + repetition);
        System.out.println("新数组的大小：" + newList.size());

    }
}

　　

生成十万条数据时间：1112
十万条数据test1方法耗时：30790
重复的数据条数：66667
新数组的大小：33333
十万条数据test2方法耗时：518
重复的数据条数：66667
新数组的大小：33333