ConcurrentSkipListMap example to make map unmodifiable in java

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import java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentSkipListMap;
/** Copyright (c), AnkitMittal */
public class ConcurrentSkipListMapUnmodifiableExample {
   public static void main(String args[]){
          Map<Integer,String> concurrentSkipListMap=new ConcurrentSkipListMap<Integer,String>();
          concurrentSkipListMap.put(11, "ankit");
          concurrentSkipListMap.put(21, "mittal");
          concurrentSkipListMap.put(31, "javaMadeSoEasy");
          //getting unmodifiable ConcurrentSkipListMap
          Map<Integer,String> unmodifiableMap = Collections.unmodifiableMap(concurrentSkipListMap);
          * Now any attempt to modify map will throw java.lang.UnsupportedOperationException
Exception in thread "main" java.lang.UnsupportedOperationException
   at java.util.Collections$UnmodifiableMap.put(Unknown Source)
   at concurrentSkipListMap_unmodifiable.concurrentSkipListMapTest.main(


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