Java Collections .unmodifiableMap ( Map <? extends K,? extends V> m)
Syntax
Collections.unmodifiableMap(Map <? extends K,? extends V> m) has the following syntax.
public static <K,V> Map <K,V> unmodifiableMap(Map <? extends K,? extends V> m)
Example
In the following code shows how to use Collections.unmodifiableMap(Map <? extends K,? extends V> m) method.
import java.util.Collections;
import java.util.Hashtable;
import java.util.Map;
/*ww w . ja v a 2 s.c o m*/
public class Main {
public static void main(String[] s) {
//object hash table
Hashtable<String,String> table = new Hashtable<String,String> ();
// populate the table
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "from java2s.com");
System.out.println("Initial collection: "+table);
// create unmodifiable map
Map<String,String> m = Collections.unmodifiableMap(table);
// try to modify the collection
m.put("key3", "value3");
}
}
The code above generates the following result.
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