CODEWITHSUNDEEP
java
Srinath Murugula
Srinath Murugula

Reputation: 582

How to remove duplicates in following java code?

I have written the following code and i am getting all the duplicates even i have used set.

private void validatingpswwithpattern(String password) throws IOException

  {
            List<String[]> list=new ArrayList<String[]>();
            list.add(new String[]{"raj","duvva","sathish"});
            list.add(new String[]{"raj","duvva","sathish"});
            list.add(new String[]{"raj","duvva","sathish"});
            list.add(new String[]{"raj","duvva","sathish"});
            list.add(new String[]{"raj","duvva","sathish"});
            list.add(new String[]{"raj","duvva","sathish"});


            Set<String[]> hs = new HashSet<String[]>();
             hs.addAll(list);
             list.clear();
             list.addAll(hs);
             System.out.println(list);
}

Upvotes: 3

Views: 108

Answers (3)

Shiladittya Chakraborty
Shiladittya Chakraborty

Reputation: 4418

You can do in the following way. If you want to remove duplicate elements, then you can do something in this way.

List<String[]> list=new ArrayList<String[]>();
list.add(new String[]{"raj","duvva","sathish"});
list.add(new String[]{"raj","duvva","sathish"});
list.add(new String[]{"raj","duvva","sathish"});
list.add(new String[]{"raj","duvva","sathish"});
list.add(new String[]{"raj","duvva","sathish"});
list.add(new String[]{"raj","duvva","sathish"});

TreeSet<String[]> set = new TreeSet<String[]>(new Comparator<String[]>() {    
  @Override
  public int compare(String[] o1, String[] o2) {
    return Arrays.equals(o1, o2)? 0 : 1;
  }
});
set.addAll(list);

list = new ArrayList<String[]>(set);

Upvotes: 0

LoganMzz
LoganMzz

Reputation: 1619

If you want to use HashSet you need to wrap your String[] into a List using Arrays.asList.

Upvotes: 0

Eran
Eran

Reputation: 393851

Since arrays don't override the default implementation of hashCode and equals from Object class, HashSet is useless for eliminating duplicates.

You could use a TreeSet and supply a Comparator<String[]> that would determine when two String arrays are equal.

TreeSet<String[]> set = new TreeSet<> (new Comparator<String[]>() {
  public int compare(String[] o1, String[] o2)
  {
    // write here logic to determine whether o1<o2 (return -1) or
    //                                       o1>o2 (return 1) or 
    //                                       o1 is equal to o2 (return 0)
  }
});
set.addAll(list);

Upvotes: 6

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