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Java ArrayList ensureCapacity() Method with Example

ArrayList Class ensureCapacity() method: Here, we are going to learn about the ensureCapacity() method of ArrayList Class with its syntax and example.
Submitted by Preeti Jain, on January 18, 2020

ArrayList Class ensureCapacity() method

• ensureCapacity() method is available in java.util package.
• ensureCapacity() method is used to ensure the capacity of this Arraylist (i.e. It can save minimum the number of elements given by the parameter).
• ensureCapacity() method is a non-static method so it is accessible with the class object and if we try to access the method with the class name then we will get an error.
• ensureCapacity() method does not throw an exception at the time of ensuring capacity.

Syntax:

    public void ensureCapacity(int minCap);

Parameter(s):

• int minCap – represents the targeted minimum capacity.

Return value:

The return type of the method is void, it returns nothing.

Example:

// Java program to demonstrate the example 
// of void ensureCapacity(int) method of ArrayList.

import java.util.*;

public class EnsureCapacityOfArrayList {
    public static void main(String[] args) {
        // Create an ArrayList with initial 
        // capacity of storing elements

        ArrayList < String > arr_l = new ArrayList < String > (10);

        // By using add() method is to add 
        // elements in this ArrayList
        arr_l.add("C");
        arr_l.add("C++");
        arr_l.add("JAVA");
        arr_l.add("DOTNET");
        arr_l.add("PHP");

        // By using ensureCapacity(int) method is to
        // ensure the capacity to store 30 elements
        // of this ArrayList
        arr_l.ensureCapacity(30);

        // Display ArrayList
        System.out.println("arr_l.ensureCapacity(30) : " + arr_l);
    }
}

Output

arr_l.ensureCapacity(30) : [C, C++, JAVA, DOTNET, PHP]