Vector removeAll() Method in Java

The java.util.vector.removeAll(Collection col) method is used to remove all the elements from the vector, present in the collection specified. 

Syntax:

Vector.removeAll(Collection col)

Parameters: This method accepts a mandatory parameter col which is the collection whose elements are to be removed from the vector. 

Return Value: This method returns true if the vector is altered due to the operation at all, else False. Exception: The method throws NullPointerException if the specified collection is null. 

Below programs illustrate the Java.util.Vector.removeAll(Collection col) method: 

Program 1:

Java

// Java code to illustrate removeAll()
import java.util.*;

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

        // Creating an empty Vector
        Vector<String> vec_tor = new Vector<String>();

        // Use add() method to add elements in the Vector
        vec_tor.add("Geeks");
        vec_tor.add("for");
        vec_tor.add("Geeks");
        vec_tor.add("10");
        vec_tor.add("20");

        // Output the Vector
        System.out.println("Vector: " + vec_tor);

        // Creating an empty Vector
        Vector<String> colvec_tor = new Vector<String>();

        // Use add() method to add elements in the Vector
        colvec_tor.add("Geeks");
        colvec_tor.add("for");
        colvec_tor.add("Geeks");

        // Remove the head using remove()
        boolean changed = vec_tor.removeAll(colvec_tor);

        // Print the result
        if (changed)
            System.out.println("Collection removed");
        else
            System.out.println("Collection not removed");

        // Print the final Vector
        System.out.println("Final Vector: " + vec_tor);
    }
}

Output:

Vector: [Geeks, for, Geeks, 10, 20]
Collection removed
Final Vector: [10, 20]

Program 2:

Java

// Java code to illustrate removeAll()
import java.util.*;

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

        // Creating an empty Vector
        Vector<Integer> vec_tor = new Vector<Integer>();

        // Use add() method to add elements in the Vector
        vec_tor.add(1);
        vec_tor.add(2);
        vec_tor.add(3);
        vec_tor.add(10);
        vec_tor.add(20);

        // Output the Vector
        System.out.println("Vector: " + vec_tor);

        // Creating an empty Vector
        Vector<Integer> colvec_tor = new Vector<Integer>();

        // Use add() method to add elements in the Vector
        colvec_tor.add(30);
        colvec_tor.add(40);
        colvec_tor.add(50);

        // Remove the head using remove()
        boolean changed = vec_tor.removeAll(colvec_tor);

        // Print the result
        if (changed)
            System.out.println("Collection removed");
        else
            System.out.println("Collection not removed");

        // Print the final Vector
        System.out.println("Final Vector: " + vec_tor);
    }
}

Output:

Vector: [1, 2, 3, 10, 20]
Collection not removed
Final Vector: [1, 2, 3, 10, 20]

Time complexity: O(n^2). // n is the size of the vector.
Auxiliary Space: O(n).