Vector addAll() Method in Java

java.util.Vector.addAll(Collection C): This method is used to append all of the elements from the collection passed as a parameter to this function to the end of a vector keeping in mind the order of return by the collection’s iterator. 

Syntax:

boolean addAll(Collection C)

Parameters: The method accepts a mandatory parameter C which is a collection of ArrayList. It is the collection whose elements are needed to be appended at the end of the vector. 

Return Value: The method returns True if at least one action of append is performed, else False. 

Below program illustrate the Java.util.Vector.addAll() method: 

Java

// Java code to illustrate boolean addAll()
import java.util.*;
import java.util.ArrayList;

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

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

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

        // A collection is created
        Collection<String> c = new ArrayList<String>();
        c.add("A");
        c.add("Computer");
        c.add("Portal");
        c.add("for");
        c.add("Geeks");

        // Displaying the Vector
        System.out.println("The Vector is: " + vt);

        // Appending the collection to the vector
        vt.addAll(c);

        // Clearing the vector using clear() and displaying
        System.out.println("The new vector is: " + vt);
    }
}

Output:

The Vector is: [Geeks, for, Geeks, 10, 20]
The new vector is: [Geeks, for, Geeks, 10, 20, A, Computer, Portal, for, Geeks]

Time complexity: O(n + m). // O(n) is the number of elements in the vector and O(m) is for the collection of elements.
Auxiliary Space: O(n+m).

java.util.Vector.addAll(int index, Collection C): This method is used to append all of the elements from the collection passed as a parameter to this function at a specific index or position of a vector. 

Syntax:

boolean addAll(int index, Collection C)

• Parameters: This function accepts two parameters as shown in the above syntax and are described below.
  • index: This parameter is of integer datatype and specifies the position in the vector starting from where the elements from the container will be inserted.
  • C: It is a collection of ArrayList. It is the collection whose elements are needed to be appended.