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快速从list集合中去除重复的对象

import java.util.ArrayList;import java.util.Collection;import java.util.Collections;import java.util.HashSet;import java.util.Iterator;import java.util.List;import java.util.Set;//从List集合中去除重复对象public class DistinctList {    public static void main(String[] args) {        String[] ar1 = { "8", "8", "9", "9" ,"0","9"};        String[] ar2 = { "张三", "张三", "李四", "张三", "王五", "李四" };        String[] ar3 = { "A", "A", "C", "A", "C", "D" };        String[] ar4 = { "12", "18", "19", "19", "10", "19" };        List<String> list = new ArrayList<String>();        Collections.addAll(list, ar1);        //List<String> list = Arrays.asList(ar2);        test1(list);    }    public static void test1(List list){        print(list);        Set set = new HashSet(list);        System.out.println("==================");        print(set);    }    public static void print(Collection coll){        Iterator iterator = coll.iterator();         while(iterator.hasNext()){             String i = (String)iterator.next();                               System.out.println(i);           }      }}

    SELECT * FROM A A1 WHERE IS EXISTS(SELECT 1 FROM A A2 WHERE A1.NAME=A2.NAME AND A1.ID>A2.ID);

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