HashSet去除List重复元素

使用Hashset 去重复

例一，List<String> 去重复

public class main {
	public static void main(String[] args) {

		List<String> list = new ArrayList<>();
		list.add("李菊福");
		list.add("狗娃");
		list.add("尼古拉斯赵四");
		list.add("尼古拉斯赵四");
		list.add("尼古拉斯赵四");
		list.add("刘能");
		list.add("刘能");
		list.add("阿里郎");
		System.out.println("排序前");
		for (String string : list) {
			System.out.println(string);
		}
                //排序
		HashSet h = new HashSet(list);
		list.clear();
		list.addAll(h);

		System.out.println("排序后");
		for (String string : list) {
			System.out.println(string);
		}		 
	}
		
}

打印结果

-----去重前----
李菊福
狗娃
尼古拉斯赵四
尼古拉斯赵四
尼古拉斯赵四
刘能
刘能
阿里郎

-------去重后--------
狗娃
李菊福
阿里郎
尼古拉斯赵四
刘能

 

例二，List<Map<String,String>> 去重复

	 public static void main(String[] args) {
		 
	        List<Map<String,String>> list = new ArrayList();
	        Map<String,String> map1 = new HashMap<String, String>();
	        Map<String,String> map2 = new HashMap<String, String>();
	        Map<String,String> map3 = new HashMap<String, String>();
	        Map<String,String> map4 = new HashMap<String, String>();
	        Map<String,String> map5 = new HashMap<String, String>();
	        Map<String,String> map6 = new HashMap<String, String>();
	        Map<String,String> map7 = new HashMap<String, String>();
	        
	        map1.put("custName","shoes");
	        map1.put("productId","1");
	        map2.put("custName","shoes");
	        map2.put("productId","2");
	        map3.put("custName","hat");
	        map3.put("productId","3");
	        map4.put("custName","hat");
	        map4.put("productId","3");
	        map5.put("custName","shoes");
	        map5.put("productId","2");
	        map6.put("custName","clothes");
	        map6.put("productId","2");
	        map7.put("custName","clothesSample");
	        map7.put("productId","2");
	        
	        list.add(map1);
	        list.add(map2);
	        list.add(map3);
	        list.add(map4);
	        list.add(map5);
	        list.add(map6);
	        list.add(map7);	       
	         
	        System.out.println("去重前");
	        for (Map<String,String> map : list) {
	            System.out.println(map.get("custName")+ " : " +map.get("productId"));
	        }
	        //去重
	        HashSet h = new HashSet(list);
	        list.clear();
	        list.addAll(h);
	        
	        System.out.println("-----");
	        System.out.println("去重后");
	        for (Map<String,String> map : list) {
	            System.out.println(map.get("custName")+ " : " +map.get("productId"));
	        }
	          
	    }　

打印

去重前
shoes : 1
shoes : 2
hat : 3
hat : 3
shoes : 2
clothes : 2
clothesSample : 2
-----
去重后
clothes : 2
shoes : 2
clothesSample : 2
shoes : 1
hat : 3