import java.util.*;
import java.lang.reflect.*;

public class ImmutableMap<K,V> extends ReadOnlyMap<K,V> {

  public ImmutableMap(Map<K,V> map) {
      // must use a static method here
      super((Map<K,V>) ImmutableMap.copyMap(map));
  }

  public ImmutableMap(K[] keys, V[] values) {
      super(keys,values);
  }
    
    // copy to make sure no mods can happen
    // but try to keep some class
    // e.g. for a TreeMap generate a TreeMap 
    // and so on ...
    static private Map copyMap(Map map) {
	Class mapClass = map.getClass();
	try {
	    // if the input map supports cloning, use it
	    Method m = mapClass.getMethod("clone");
	    return (Map) m.invoke(map);
	} catch (Exception e1) {
	    try {
		// else check whether a constructor taking a map is supported
		Constructor cons = mapClass.getConstructor(Map.class);
		return (Map) cons.newInstance(map);
	    } catch (Exception e2) {
		// if none of the above, simply resort to a HashMap
		return new HashMap(map);
	    }
	}
    }

}