Working with hashMaps

I want to avoid开发者_开发问答 the use of for loop for iterating through the HaspMap for finding a key and then picking up the value corresponding to that key...Can anyone help me to implement the same...? Below given is my code using forloop which i would like to replace with containsKey function()

 for (Entry<Long, Long> entry : sessionTimeStampHash.entrySet()) 
 //if(sessionTimeStampHash.containsKey(sessionID)) 
 {
    if (entry.getKey().equals(sessionID)) 
    {
        sessionTimeStamp = entry.getValue();
    }
 }

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You don't need a loop at all. Maps are associative collections, which means they are designed and optimized for fast key-based lookup. A map is meant to be used this way:

sessionTimeStamp = sessionTimeStampHash.get(sessionID);
if (sessionTimeStamp != null) {
  // do something with sessionTimeStamp
}

Or using containsKey():

if (sessionTimeStampHash.containsKey(sessionID)) {
  sessionTimeStamp = sessionTimeStampHash.get(sessionID);
  // do something with sessionTimeStamp
}

See the Java Tutorial to learn more about Maps and other collections.

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if(sessionTimeStampHash.contains(sessionID) {
  sessionTimeStamp  = sessionTimeStampHash.get(sessionID);
} else {
   //Create session 
  sessionTimeStamp = getSessionTimeStamp();
  sessionTimeStampHash.put(sessionId, sessionTimeStamp);
}

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