Using HashMap.. can be one of the way.

HashMap hs = new HashMap();
    
hs.put("amit","989213232");
hs.put("john","989211422");
hs.put("Alex","989214578");

Shahnawaz Sheikh---sorry to say but don't you think that ur
ans is having some flaw...u r correct that phone no can be
store in HasMap but u have taken name as key but name can be
repeated while ph no is unique so don't u think that phone
no should be key in upper hash map.

We will have to assume that the names are going to be 
unique. We may have a situation, that one number is common 
for husband & wife or between friends etc. I mean, there is 
a possibility, right? And normally you get the name of the 
person and you have to find the phone number (I dont think 
its going to be the other way round...in normal cases). 
Then we need to have the name as the "Key", rather than 
as "Value". Let me know, your thoughts on the same. Thanks.

Sorry,sunny i am not agree with your scenario that one
number is common for husband & wife or between friends
etc.It is not real life scenario, phone no. are always
register with single person name ,that might be possible two
or many persons have
name,if we use HashMap , the Key might be different than
name  like empid or securityid or some unique parameter.
Thanks