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PORetrieving key from value in hashtable in Java
 

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  1. PORetrieving key from value in hashtable in Java
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    <p>I am a new bie to the world of collections but still, In my below class I have hashtable as I have to choose hashtable and I want to retrieve the key basis on the value , below is my class..</p> <pre><code>public class KeyFromValueExample { public static void main(String args[]) { Hashtable table = new Hashtable(); table.put("Sony", "Bravia"); table.put("Samsung", "Galaxy"); table.put("Nokia", "Lumia"); System.out.println("does hash table has Lumia as value : " + table.containsValue("Lumia")); System.out.println("does hash table Lumia as key : " + table.containsKey("Lumia")); //finding key corresponding to value in hashtable - one to one mapping String key= null; String value="Lumia"; for(Map.Entry entry: table.entrySet()){ if(value.equals(entry.getValue())){ key = entry.getKey(); break; //breaking because its one to one map } } System.out.println("got key from value in hashtable key: "+ key +" value: " + value); //finding key corresponding to value in hashtable - one to many mapping table.put("HTC", "Lumia"); Set keys = new HashSet(); for(Map.Entry entry: table.entrySet()){ if(value.equals(entry.getValue())){ keys.add(entry.getKey()); //no break, looping entire hashtable } } System.out.println("keys : " + keys +" corresponding to value in hash table: "+ value); </code></pre> <p>Output :-</p> <pre><code>does hash table has Lumia as value : true does hash table has Lumia as key : false got key from value in hashtable key: Nokia value: Lumia keys : [Nokia, HTC] corresponding to value in hash talbe: Lumia </code></pre> <p>Now please advis is there any other better way to achieve the same thing, Please advise if other better alternatives are there.</p>
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