java.util.Vector.retainAll() Method

Description

The retainAll(Collection<?> c) method is used to retain only the elements in this Vector that are contained in the specified Collection. In other words, removes from this Vector all of its elements that are not contained in the specified Collection.

Declaration

Following is the declaration for java.util.Vector.retainAll() method

public boolean retainAll(Collection<?> c)

Parameters

c − This is the collection of elements to be retained in this Vector.

Return Value

The method call returns true if this Vector is changed as a result of the call.

Exception

NullPointerException − This exception is thrown if the specified collection is null.

Example

The following example shows the usage of java.util.Vector.retainAll() method.

package com.tutorialspoint;

import java.util.Vector;

public class VectorDemo {
   public static void main(String[] args) {

      // create an empty Vector vec with an initial capacity of 7      
      Vector<Integer> vec = new Vector<Integer>(7);
      Vector<Integer> vecretain = new Vector<Integer>(4);

      // use add() method to add elements in the vector
      vec.add(1);
      vec.add(2);
      vec.add(3);
      vec.add(4);
      vec.add(5);
      vec.add(6);
      vec.add(7);

      // this elements will be retained
      vecretain.add(5);
      vecretain.add(3);
      vecretain.add(2);

      System.out.println("Calling retainAll()");
      vec.retainAll(vecretain);

      // let us print all the elements available in vector
      System.out.println("Numbers after removal :- "); 
      
      for (Integer number : vec) {         
         System.out.println("Number = " + number);
      }           
   }    
} 

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

Calling retainAll()
Numbers after removal :- 
Number = 2
Number = 3
Number = 5

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