HashMap Duplicate Key should give error?

[Em Aiy]

the following code should have given me error for "duplicate" key. but it is not giving. why?

Map<String, Integer> oMap = new HashMap<String, Integer>();

for (int i = 0; i < 2; i++){
      String word = "hello";
      oMap.put(word, i);
}

[Anuj Prashar]

It is just replacing the value mapped by key 'word'. It is not creating any new entry in map.

After first call of put method a mapping is created.
And for any subsequent call to put method if the map contained a mapping for key, the old value is replaced.

[Em Aiy]

Anuj Prashar wrote:It is just replacing the value mapped by key 'word'. It is not creating any new entry in map.

but it should give error "duplicate entry" (word). isn't it so ?

[Anuj Prashar]

check this this

After first call, subsequent call to put method will replace old value if mapping for key you are using in your put method already exist.