CODEWITHSUNDEEP
javaarraylisthashmapmaps
user10274438
user10274438

Reputation: 123

How to replace duplicate elements in Hash Map

I'm trying to replace duplicate values in Hash Map with new unique ids. so that order of elements is not lost but duplicate values alone get changed to new ones.

HashMap<Integer,String> hm=new HashMap<Integer,String>();      
  hm.put(100,"1111111111");    
  hm.put(101,"5252");    
  hm.put(102,"1111111111");
  hm.put(103,"1111111111");

  for(int i=0;i<hm.size;hm++){
  String uuids = UUID.randomUUID().toString().replace("-", "");
  hm.put(i, uuids);
  }

Upvotes: 0

Views: 150

Answers (2)

TongChen
TongChen

Reputation: 1430

First,reverse the key and value in your hm map into a Multimap，then rewrite value to your own map.code like this:

Multimap<String,Integer> reverseMap = ArrayListMultimap.create();
hm.entrySet().stream()
    .forEach(integerStringEntry -> reverseMap.put(integerStringEntry.getValue(),integerStringEntry.getKey()));
reverseMap.keySet().forEach(s -> reverseMap.get(s).stream()
    .skip(1L)
    .forEach(integer -> {
        String uuids = UUID.randomUUID().toString().replace("-", "");
        hm.put(integer,uuids);
    }));

System.out.println(hm);

The output is：

{100=1111111111, 101=5252, 102=2e3586d248e3413687ff55dc17817c7d, 103=4589857}

Upvotes: 1

Kartik
Kartik

Reputation: 7917

You were close:

Map<Integer, String> hm = new LinkedHashMap<>();
hm.put(100, "1111111111");
hm.put(101, "5252");
hm.put(102, "1111111111");
hm.put(103, "4589857");

Set<String> seen = new HashSet<>();
for (Map.Entry<Integer, String> e : hm.entrySet()) {
    if (!seen.add(e.getValue())) { //if (the 'seen' set already has that value)
        hm.replace(e.getKey(), UUID.randomUUID().toString().replace("-", ""));
    }
}

System.out.println(hm);

Output:

{100=1111111111, 101=5252, 102=ba297d9412654591826d4e496f643b4c, 103=4589857}

Upvotes: 4

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