Collections class in java ?

 The Collections class in Java provides utility methods for working with collections, such as List, Set, and Map. It offers various static methods to perform common operations like sorting, searching, and synchronizing collections. Here are some key functionalities provided by the Collections class:

1. Sorting Collections:

   • sort(List<T> list): Sorts the specified list into ascending order.
   • sort(List<T> list, Comparator<? super T> c): Sorts the specified list according to the order induced by the specified comparator.

2. Searching Collections:

   • binarySearch(List<? extends Comparable<? super T>> list, T key): Searches the specified list for the specified object using the binary search algorithm.
   • binarySearch(List<? extends T> list, T key, Comparator<? super T> c): Searches the specified list for the specified object using the binary search algorithm.

3. Synchronization of Collections:

   • synchronizedList(List<T> list): Returns a synchronized (thread-safe) list backed by the specified list.
   • synchronizedSet(Set<T> s): Returns a synchronized (thread-safe) set backed by the specified set.
   • synchronizedMap(Map<K,V> m): Returns a synchronized (thread-safe) map backed by the specified map.

4. Creating Immutable Collections:

   • emptyList(), emptySet(), emptyMap(): Returns an immutable empty list, set, or map respectively.
   • singletonList(T o), singleton(T o), singletonMap(K key, V value): Returns an immutable list, set, or map containing only the specified object or key-value pair.

5. Miscellaneous Utility Methods:

   • reverse(List<?> list): Reverses the order of the elements in the specified list.
   • shuffle(List<?> list): Randomly permutes the elements in the specified list.
   • copy(List<? super T> dest, List<? extends T> src): Copies all of the elements from one list into another.
   • frequency(Collection<?> c, Object o): Returns the number of elements in the specified collection equal to the specified object.