Collections unmodifiableCollection() method in Java with Examples Last Updated : 08 Oct, 2018 Comments Improve Suggest changes Like Article Like Report The unmodifiableCollection() method of java.util.Collections class is used to return an unmodifiable view of the specified collection. This method allows modules to provide users with "read-only" access to internal collections. Query operations on the returned collection "read through" to the specified collection, and attempts to modify the returned collection, whether direct or via its iterator, result in an UnsupportedOperationException. The returned collection does not pass the hashCode and equals operations through to the backing collection, but relies on Object's equals and hashCode methods. This is necessary to preserve the contracts of these operations in the case that the backing collection is a set or a list. The returned collection will be serializable if the specified collection is serializable. Syntax: public static <T> Collection<T> unmodifiableCollection(Collection<? extends T> c) Parameters: This method takes the collection as a parameter for which an unmodifiable view is to be returned. Return Value: This method returns an unmodifiable view of the specified collection. Below are the examples to illustrate the unmodifiableCollection() method Example 1: Java // Java program to demonstrate // unmodifiableCollection() method // for <Character> Value import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { // creating object of ArrayList<Character> List<Character> list = new ArrayList<Character>(); // populate the list list.add('X'); list.add('Y'); // printing the list System.out.println("Initial list: " + list); // getting unmodifiable list // using unmodifiableCollection() method Collection<Character> immutablelist = Collections .unmodifiableCollection(list); } catch (UnsupportedOperationException e) { System.out.println("Exception thrown : " + e); } } } Output: Initial list: [X, Y] Example 2: For UnsupportedOperationException Java // Java program to demonstrate // unmodifiableCollection() method // for UnsupportedOperationException import java.util.*; public class GFG1 { public static void main(String[] argv) throws Exception { try { // creating object of ArrayList<Character> List<Character> list = new ArrayList<Character>(); // populate the list list.add('X'); list.add('Y'); // printing the list System.out.println("Initial list: " + list); // getting unmodifiable list // using unmodifiableCollection() method Collection<Character> immutablelist = Collections .unmodifiableCollection(list); // Adding element to new Collection System.out.println("\nTrying to modify" + " the unmodifiableCollection"); immutablelist.add('Z'); } catch (UnsupportedOperationException e) { System.out.println("Exception thrown : " + e); } } } Output: Initial list: [X, Y] Trying to modify the unmodifiableCollection Exception thrown : java.lang.UnsupportedOperationException Comment More infoAdvertise with us Next Article Collections unmodifiableCollection() method in Java with Examples rohitprasad3 Follow Improve Article Tags : Advance Java Java-Collections Java - util package Java-Functions Practice Tags : Java-Collections Similar Reads Collections unmodifiableList() method in Java with Examples The unmodifiableList() method of java.util.Collections class is used to return an unmodifiable view of the specified list. 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