Stack ensureCapacity() method in Java with Example

Last Updated : 24 Dec, 2018

The ensureCapacity() method of Java.util.Stack class increases the capacity of this Stack 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

// 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 Stack<Integer>
            Stack<Integer>
                stack = new Stack<Integer>();

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

            // Print the Stack
            System.out.println("Stack: "
                               + stack);

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

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

        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

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

Example 2:

Java

// 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 Stack<Integer>
            Stack<String>
                stack = new Stack<String>();

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

            // Print the Stack
            System.out.println("Stack: "
                               + stack);

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

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

        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

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

Stack elements() method in Java with Example

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