Vector ensureCapacity() method in Java with Example

The ensureCapacity() method of Java.util.Vector class increases the capacity of this Vector instance, if necessary, to ensure that it can hold at least the number of elements specified by the minimum capacity argument.

Syntax:

public void ensureCapacity(int minCapacity)

Parameters: This method takes the desired minimum capacity as a parameter.

Below are the examples to illustrate the ensureCapacity() method.

Example 1:

// Java program to demonstrate
// ensureCapacity() method for Integer value

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {

        try {

            // Creating object of Vector<Integer>
            Vector<Integer>
                vector = new Vector<Integer>();

            // adding element to vector
            vector.add(10);
            vector.add(20);
            vector.add(30);
            vector.add(40);

            // Print the Vector
            System.out.println("Vector: "
                               + vector);

            // ensure that the Vector
            // can hold upto 5000 elements
            // using ensureCapacity() method
            vector.ensureCapacity(5000);

            // Print
            System.out.println("Vector can now"
                               + " surely store upto"
                               + " 5000 elements.");
        }

        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

Vector: [10, 20, 30, 40]
Vector can now surely store upto 5000 elements.

Example 2:

// Java program to demonstrate
// ensureCapacity() method for String value

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {

        try {

            // Creating object of Vector<Integer>
            Vector<String>
                vector = new Vector<String>();

            // adding element to vector
            vector.add("A");
            vector.add("B");
            vector.add("C");
            vector.add("D");

            // Print the Vector
            System.out.println("Vector: "
                               + vector);

            // ensure that the Vector
            // can hold upto 400 elements
            // using ensureCapacity() method
            vector.ensureCapacity(400);

            // Print
            System.out.println("Vector can now"
                               + " surely store upto"
                               + " 400 elements.");
        }

        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

Vector: [A, B, C, D]
Vector can now surely store upto 400 elements.