java.util.Collections.unmodifiableSet() Method


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Description

The unmodifiableSet() method Returns an unmodifiable view of the specified set.

Declaration

Following is the declaration for java.util.Collections.unmodifiableSet() method.

public static <T> boolean addAll(Collection<? super T> c, T.. a)								 

Parameters

  • s -- This is the set for which an unmodifiable view is to be returned.

Return Value

The method call returns an unmodifiable view of the specified set.

Exception

  • NA

Example

The following example shows the usage of java.util.Collections.unmodifiableSet()

package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String[] s) {
   // create set
   Set<String> set = new HashSet<String>();
      
   // populate the set
   set.add("Welcome");
   set.add("to");
   set.add("TP");
      
   System.out.println("Initial set value: "+set);
      
   // create unmodifiable set
   Set unmodset = Collections.unmodifiableSet(set);

   // try to modify the set
   unmodset.add("Hello");
   }
}

Let us compile and run the above program, this will produce the following result.

Initial set value: [to, Welcome, TP]
Exception in thread "main" java.lang.UnsupportedOperationException

java_util_collections.htm

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