How to remove binary arraylist values

Question

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

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

I used the 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);
  }

It works great if it finds the same duplicate values. However, if you look carefully at my data, there are several duplicate entries, but not in the same order. For example, a, b, 12 and b, a, 12 are but in a different order.

How to remove this type of duplicate records from arraylist?

thank

Answer 1

, String. . (), , .

EDIT: .

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;
   }
}

, , 12

, , 3

, , 3

Answer 2

"Foo" "String", "removeDuplicate" :

public class Foo {
    private String s1;
    private String s2;
    private String s3;

    public Foo(String s1, String s2, String s3) {
     this.s1 = s1;
     this.s2 = s2;
     this.s3 = s3;
    }

 @Override
    public int hashCode() {
     final int prime = 31;
     int result = 1;
     result = prime * result + ((s1 == null) ? 0 : s1.hashCode());
     result = prime * result + ((s2 == null) ? 0 : s2.hashCode());
     result = prime * result + ((s3 == null) ? 0 : s3.hashCode());
     return result;
    }

 @Override
    public boolean equals(Object obj) {
     if (this == obj)
      return true;
     if (obj == null)
      return false;
     if (getClass() != obj.getClass())
      return false;
     Foo other = (Foo) obj;
     //Notice here: 'a,b,12' and 'b,a,12' will be same
     if(fieldsAsList().containsAll(other.fieldsAsList())){
      return true;
     }

     return false;
    }

 private List<String> fieldsAsList(){
  ArrayList<String> l = new ArrayList<String>(3);
  l.add(s1);
     l.add(s2);
     l.add(s3);
     return l;
 }    
}

arList ArrayList < Foo>.

Answer 3

(), . equals() hashCode(). HashSet .

Answer 4

... ( )

fooobar.com/questions/19089 / ...

Answer 5

As ArrayListwe can not directly delete any duplicate items. We can achieve this with sets, because sets do not allow duplication, so it is better to use classes HashSetor LinkedHashSet. See link .