Java tutorial
import java.util.Collections; import java.util.Hashtable; import java.util.Map; public class Main { public static void main(String[] s) { Hashtable<String, String> table = new Hashtable<String, String>(); table.put("1", "Sunday"); table.put("2", "Monday"); table.put("3", "Tuesday"); table.put("4", "Wednesday"); table.put("5", "Thursday"); table.put("6", "Friday"); table.put("7", "Saturday"); System.out.println("Initial collection: " + table); Map m = Collections.unmodifiableMap(table); // m.put("key3", "value3"); } }