package thinkinginjava.containers;

// Using the Collections.unmodifiable methods.

import java.util.*;

import thinkinginjava.util.Countries;

import static thinkinginjava.util.Print.*;

public class ReadOnly {

static Collection<String> data = new ArrayList<String>(Countries.names(6));

public static void main(String[] args) {

Collection<String> c = Collections

.unmodifiableCollection(new ArrayList<String>(data));

print(c); // Reading is OK

// ! c.add("one"); // Can't change it

List<String> a = Collections.unmodifiableList(new ArrayList<String>(

data));

ListIterator<String> lit = a.listIterator();

print(lit.next()); // Reading is OK

// ! lit.add("one"); // Can't change it

Set<String> s = Collections.unmodifiableSet(new HashSet<String>(data));

print(s); // Reading is OK

// ! s.add("one"); // Can't change it

// For a SortedSet:

Set<String> ss = Collections.unmodifiableSortedSet(new TreeSet<String>(

data));

Map<String, String> m = Collections

.unmodifiableMap(new HashMap<String, String>(Countries

.capitals(6)));

print(m); // Reading is OK

// ! m.put("Ralph", "Howdy!");

// For a SortedMap:

Map<String, String> sm = Collections

.unmodifiableSortedMap(new TreeMap<String, String>(Countries

.capitals(6)));

}

}