COLLECTIONS class provides static method to MAKE a Collection unmodifiable. Each of the SIX core collection interfaces -Collection, Set, List, Map, SortedSet, and SortedMap - has one static factory method.

public static <T> Collection<T> unmodifiableCollection(Collection<? extends T> C);

public static <T> Set<T> unmodifiableSet(Set<? extends T> s);

public static <T> List<T> unmodifiableList(List<? extends T> list);

public static <K,V> Map<K, V> unmodifiableMap(Map<? extends K, ? extends V> m);

public static <T> SortedSet<T> unmodifiableSortedSet(SortedSet<? extends T> s);

public static <K,V> SortedMap<K, V> unmodifiableSortedMap(SortedMap<K, ? extends V> m);

Collections class provides static method to make a Collection unmodifiable. Each of the six core collection interfaces -Collection, Set, List, Map, SortedSet, and SortedMap - has one static factory method.

public static <T> Collection<T> unmodifiableCollection(Collection<? extends T> c);

public static <T> Set<T> unmodifiableSet(Set<? extends T> s);

public static <T> List<T> unmodifiableList(List<? extends T> list);

public static <K,V> Map<K, V> unmodifiableMap(Map<? extends K, ? extends V> m);

public static <T> SortedSet<T> unmodifiableSortedSet(SortedSet<? extends T> s);

public static <K,V> SortedMap<K, V> unmodifiableSortedMap(SortedMap<K, ? extends V> m);