How to access Null key value of an HashMap

[Ravi Kiran Va]

Hi ,

As HashMap allows to add one NULL key .
Can anybody please let me know .

How can we access the value of this null key ??

HashMap map = new HashMap();
map.put(null, ''test")

How can i access the value called as 'test' ??

Thanks in advnace .

[Christophe Verré]

By curiosity, did you try get(null) ?

[Wouter Oet]

get(null);???

[Ninad Kuchekar]

You could have tried this yourself....

  map.get(null);  

FYI, as far as I know, you can keep on adding null keys to the same HashMap except that when you try to retrieve the value it will return the latest entry into the HashMap against a null key. Correct me if I am wrong...


-Ninad

[Rob Spoor]

No, you're right. If null is allowed (it isn't in Hashtable for instance) then it behaves like any other key: calling map.put(null, value) will overwrite any previous value for the null key.

[Ninad Kuchekar]

Rob Prime wrote: No, you're right. If null is allowed (it isn't in Hashtable for instance) then it behaves like any other key: calling map.put(null, value) will overwrite any previous value for the null key.

Thanks Rob!

[Ravi Kiran Va]

I tried

 map.get(null) 

, its working .

but why did Java allowed a null key to be inserted inside a HashMap , is this behaviour would be useful anywhere ??

Thanks .

[Jaikiran Pai]

Ravi Kiran V wrote:

but why did Java allowed a null key to be inserted inside a HashMap , is this behaviour would be useful anywhere ??

http://www.coderanch.com/t/507881/java/java/HashMap

[Ninad Kuchekar]

Ravi Kiran V wrote: ... but why did Java allowed a null key to be inserted inside a HashMap , is this behaviour would be useful anywhere ??

There has already been some debate over this matter in some other thread, have a look at this for your reference.

[Ninad Kuchekar]

Jaikiran Pai wrote:
http://www.coderanch.com/t/507881/java/java/HashMap

Coincidentally, the above post has also been created by someone by the name Ravi Kiran

[Ravi Kiran Va]