What is the Vector.containsAll method in Java?

The containsAll method checks if all the elements of the specific collection object are present in the Vector object.

The Vector class is a growable array of objects. The elements of Vector can be accessed using an integer index and the size of a Vector can be increased or decreased. Read more about Vector here.

Syntax

public boolean containsAll(Collection<?> c)

This method takes the collection to be checked if it is present in the vector object.

It will return true if all the elements of the passed collection are present in the Vector object.

Working example

Please click the “Run” button below to see how the containsAll method works.

import java.util.Vector;
import java.util.ArrayList;
class containsAll {
    public static void main( String args[] ) {
        Vector<Integer> vector = new Vector<>();
        vector.add(1);
        vector.add(2);
        vector.add(3);
        ArrayList<Integer> list1 = new ArrayList<>();
        list1.add(1);
        list1.add(3);
        System.out.println("The vector is "+ vector);
        System.out.println("\nlist1 is "+ list1);
        System.out.println("If vector contains all elements of list1 : "+ vector.containsAll(list1));
        ArrayList<Integer> list2 = new ArrayList<>();
        list2.add(4);
        
        System.out.println("\nlist2 is "+ list2);
        System.out.println("If vector contains all elements of list2 : "+ vector.containsAll(list2));
        
    }
}

Explanation

In the above code:

Line 1 and 2: We imported the Vector and ArrayList class
Line 5: We created an object for the Vector class with the name vector.
Lines 6 - 8: We added three elements (1,2,3) to the above created vector object.
Line 10: We created a new ArrayList object with the name list1.
Line 11 and 12: We added the elements 1,3 to list1.
Line 16: We used the containsAll method to check if all the elements of list1 are present in the vector. In this case, true is returned. This is because all the elements (1,3) of list1 are present in the vector.
Line 18: We created a new ArrayList object with the name list2.
Line 19: We added an element 4 to list2.
Line 22: We used the conainsAll method to check if all the elements of the list2 are present in the vector. In this case, false is returned. This is because element 4 of the list2 is not present in the vector.

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