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How to Reverse HashMap, key becomes values and vice-versa

Posted on 2003-11-06
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Last Modified: 2010-07-27
I have a HashMap with key-values. Sometime, I need to know key for a given value. Could anyone let me know how to do that ?
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Question by:vinay_delhi
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4 Comments
 
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applekanna earned 200 total points
ID: 9692804
import java.util.*


  HashMap h = new HashMap();
     Iterator i = h.entrySet().iterator();
     while(i.hasNext())
     {
      Map.Entry entry = (Map.Entry)i.next();
     System.out.println(entry.getKey() + "/" + entry.getValue());
   //  if((Object) entry.getValue() == your code to compare
     }
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Expert Comment

by:applekanna
ID: 9692813
Assuming you have string for both key and value
     {
      Map.Entry entry = (Map.Entry)i.next();
     System.out.println(entry.getKey() + "/" + entry.getValue());
     String key =  (String) entry.getValue()
     String value = (String) entry.getValue();
   //  if(value.equals("some")
     }
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