HashMap - making map unmodifiable using Collections.unmodifiableMap






HashMap - making map unmodifiable using Collections.unmodifiableMap




import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
/** Copyright (c), AnkitMittal JavaMadeSoEasy.com */
public class HashMapTest {
   public static void main(String args[]){
         
          Map<Integer,String> hashMap=new HashMap<Integer,String>();
  
          hashMap.put(11, "ankit");
          hashMap.put(21, "mittal");
          hashMap.put(31, "javaMadeSoEasy");
         
          //getting unmodifiable HashMap
          Map<Integer,String> unmodifiableMap = Collections.unmodifiableMap(hashMap);
  
          /*
          * Now any attempt to modify map will throw java.lang.UnsupportedOperationException
          */
          unmodifiableMap.put(41,"java");
   }
}
/*OUTPUT
Exception in thread "main" java.lang.UnsupportedOperationException
   at java.util.Collections$UnmodifiableMap.put(Unknown Source)
   at hashMap_unmodifiable.HashMapTest.main(hashMapTest.java:24)
*/



RELATED LINKS>


HashMap - Iterate on keys by obtaining keySet, Iterate on values by obtaining values, Iterate on entry by obtaining entrySet


HashMap - synchronizing map using Collections.synchronizedMap



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