如何删除arraylist重复值 [英] how to remove arraylist duplicate values

问题描述

我正在旧系统上执行一些维护任务.我有一个包含以下值:

I am performing some maintenance tasks on an old system. I have an arraylist that contains following values:

a,b,12
c,d,3
b,a,12
d,e,3
a,b,12

我使用以下代码从数组列表中删除重复值

I used following code to remove duplicate values from arraylist

ArrayList<String> arList;
  public static void removeDuplicate(ArrayList arlList)
  {
   HashSet h = new HashSet(arlList);
   arlList.clear();
   arlList.addAll(h);
  }

它工作正常，如果它找到相同的重复值.但是，如果你仔细看我的数据，有一些重复的条目，但顺序不同.例如，a,b,12 和 b,a,12 是相同但顺序不同.

It works fine, if it finds same duplicate values. However, if you see my data carefully, there are some duplicate entries but not in same order. For example, a,b,12 and b,a,12 are same but in different order.

如何从arraylist中删除这种重复的条目?

How to remove this kind of duplicate entries from arraylist?

谢谢

推荐答案

假设条目是字符串.然后您可以对每个条目进行排序，然后进行重复检查.然后您可以将条目存储在地图中并使用 contains(key) 来查看它们是否存在.

Assuming the entries are String. Then you can sort each of the entry and then do the duplicate check. Then you can store the entry in a map and use the contains(key) to see if they exist.

添加了完整的代码示例.

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Test test = new Test();
        List<String> someList = new ArrayList<String>(); 
        someList.add("d,e,3");
        someList.add("a,b,12");
        someList.add("c,d,3");
        someList.add("b,a,12");
        someList.add("a,b,12");
            //using a TreeMap since you care about the order
        Map<String,String> dupMap = new TreeMap<String,String>();
        String key = null;
        for(String some:someList){
            key = test.sort(some);
            if(key!=null && key.trim().length()>0 && !dupMap.containsKey(key)){
                dupMap.put(key, some);
            }
        }
        List<String> uniqueList = new ArrayList<String>(dupMap.values());
        for(String unique:uniqueList){
            System.out.println(unique);
        }

    }
    private String sort(String key) {
      if(key!=null && key.trim().length()>0){
        char[] keys = key.toCharArray();
        Arrays.sort(keys);
        return String.valueOf(keys);
      }
      return null;
   }
}

印刷品:

a,b,12

c,d,3

d,e,3

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