Java Vector ensureCapacity() Method

The ensureCapacity() method of Java Vector class is used to increase the capacity of the vector which is in use, if necessary. It ensures that the vector can hold at least the number of components specified by the minimum capacity argument.

Syntax:

Following is the declaration of ensureCapacity() method:

Parameter:

DataType	Parameter	Description	Required/Optional
int	minCapacity	It is the desired minimum capacity.	Required

Returns:

The ensureCapacity() method has return type void so, it does not return anything.

Exceptions:

Compatibility Version:

Java 1.2 and above

Example 1:

import java.util.*;
public class VectorEnsureCapacityExample1 {  
	public static void main(String arg[]) {	
	     //Create an empty vector of capacity 10		
           Vector<Integer> vec = new Vector<>(10);       
           //Ensuring capacity
           vec.ensureCapacity(25);         
           //Cheking the capacity
           System.out.println("Minimum capacity of this vector: " +vec.capacity());
	     }            
}

Test it Now

Output:

Minimum capacity of this vector: 25

Example 2:

import java.util.*;
public class VectorEnsureCapacityExample2 {  
	public static void main(String arg[]) {	
		//Create an empty vector of capacity 10		
		Vector<String> vecobject = new Vector<>();
		//Add element in the vector
		vecobject.add("50"); 
		vecobject.add("green");
		vecobject.add("red"); 
		System.out.println("Element: "+vecobject);
		System.out.println("Capacity of the vector is: " +vecobject.capacity());
		//Increases the capacity of this vector
		vecobject.ensureCapacity(20); 
		System.out.println("New Capacity of the vector is:" +vecobject.capacity());
	      }            
}

Test it Now

Output:

Element: [50, green, red]
Capacity of the vector is: 10
New Capacity of the vector is:20

Example 3:

import java.util.*;
public class VectorEnsureCapacityExample3 {  
	public static void main(String arg[]) {	
		//Create an empty vector of capacity 10		
		Vector<Integer> vec = new Vector<>(5);		
	      for (int i = 0; i < 10; i++) {
	         vec.add(0,i);
	      }
	      System.out.println("Element of the vector: "+vec);
	      System.out.println("Vector size: "+vec.size());  	      
	      //Ensure the capacity of the vector and add elements
	      vec.ensureCapacity(40);
	      for (int i = 0; i < 10; i++) {
	         vec.add(0,i);
	      }    
	      System.out.println("Vector element after ensuring capacity: "+vec);
	      System.out.println("New vector size: "+vec.size());
	}            
}

Test it Now

Output:

Element of the vector: [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
Vector size: 10
Vector element after ensuring capacity: [9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
New vector size: 20

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