how to remove arraylist duplicate values

Question

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

Answer 1

Wrap the element as "Foo" instead of "String", rest of code 'removeDuplicate' remains:

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 fieldsAsList(){
  ArrayList l = new ArrayList(3);
  l.add(s1);
     l.add(s2);
     l.add(s3);
     return l;
 }    
}

Then arList will be ArrayList < Foo>.