Java Vector retainAll() Method

The retainAll() method of Java Vector class is used to retain only that elements in the vector which are contained in the specified collection. In other words, it removes all elements from this vector that are not contained in the specified collection.

Syntax

Following is the declaration of retainAll() method:

Parameter

Parameter	Description	Required/Optional
c	It is a collection of elements which will be retained in this vector, and all other elements are removed.	Required

Return

The retainAll() method returns true if the vector changed as a result of the call.

Exceptions

NullPointerException- This method has thrown an exception if the vector contains one or more null elements and the specified collection does not support null elements or if the specified collection is null.

Compatibility Version

Java 1.2 and above

Example 1

import java.util.Vector;
public class VectorRetainAllExample1 {  
	public static void main(String arg[]) {
	  //Create an empty Vec1
        Vector<Integer> vec1 = new Vector<>();
        //Add elements in the Vector1
        vec1.add(1);
        vec1.add(2);
        vec1.add(3);
        vec1.add(4);
        vec1.add(2); 
        //Create an empty Vec2
        Vector<Integer> vec2 = new Vector<>();
        //Add elements in the Vector2
        vec2.add(2);
        vec2.add(3); 
        //Displaying the Vector elements      
        System.out.println("Values in vector :" +vec1);
        //use retainAll() method
        vec1.retainAll(vec2);
        System.out.println("Values in vector :" +vec1);
	  }
}

Test it Now

Output:

Values in vector :[1, 2, 3, 4, 2]
Values in vector :[2, 3, 2]

Example 2

import java.util.Vector;
public class VectorRetainAllExample2 {  
	public static void main(String arg[]) {
	  //Create an empty Vec1
        Vector<String> vec1 = new Vector<String>();
        //Add elements in the Vector1
        vec1.add("A");
        vec1.add("B");
        vec1.add("C");
        vec1.add("10");
        vec1.add("20"); 
        //Displaying the Vector1 elements
        System.out.println("Vector: " + vec1); 
        //Create an empty Vec2
        Vector<String> vec2 = new Vector<String>(); 
        //Add elements in the Vector2
        vec2.add("A");
        vec2.add("B");
        vec2.add("C"); 
        //use retainAll() method
        boolean changed = vec1.retainAll(vec2);
        //Print the result
        if (changed)
            System.out.println("Collection retained");
        else
            System.out.println("Collection not retained");
        //Display the final Vector
        System.out.println("Final Vector: " + vec1);
	  }
}

Test it Now

Output:

Vector: [A, B, C, 10, 20]
Collection retained
Final Vector: [A, B, C]

Next TopicJava Vector

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