In this article, we will discuss how to find size or length of an ArrayList
1. ArrayList :
We can use, size() method of Collection interface to find size of an ArrayList which
- allows duplicate elements
- null elements insertion is possible
- maintains insertion-order
2. To get size of an ArrayList using size() method :
FindSizeOfAnArrayList.java
package in.bench.resources.java.collections;
import java.util.ArrayList;
import java.util.Iterator;
public class FindSizeOfAnArrayList {
public static void main(String[] args) {
// creating ArrayList object of type String
ArrayList<String> al = new ArrayList<String>();
// adding elements to ArrayList object
al.add("Sundar Pichai");
al.add("Satya Nadella");
al.add("Shiv Nadar");
al.add("Shantanu Narayen");
al.add("Sundar Pichai"); // duplicate object
al.add("Francisco D’Souza");
al.add(null); // null is allowed
int alSize = al.size();
System.out.println("Size of an ArrayList is : " + alSize);
// Iterating using Iterator of Collection interface
System.out.println("\n\nIterating ArrayList elements\n");
Iterator<String> itr = al.iterator();
while(itr.hasNext()) {
System.out.println(itr.next());
}
}
}
Output:
Size of an ArrayList is : 7
Iterating ArrayList elements
Sundar Pichai
Satya Nadella
Shiv Nadar
Shantanu Narayen
Sundar Pichai
Francisco D’Souza
null
From above example, ArrayList
- allows duplicate elements
- null object is allowed
- while iterating insertion-order is maintained
Related Articles:
- Java – Creating ArrayList using nCopies method of Collections class
- Java – How to get size or length of an ArrayList ?
- Java – Adding element to ArrayList at specified index position
- Java – Remove element from ArrayList at specified index position
- Java – How to delete a element and delete all elements of an ArrayList ?
- Java- How to get sublist from ArrayList ?
- Java – How to check whether particular element is present in ArrayList ?
- Java – Comparing two ArrayList objects using containsAll() method
- Java – Adding one ArrayList to another ArrayList using addAll() method
- Java – Replacing ArrayList element with new value using set() method
- Java – Various ways to iterate through ArrayList
- Java – How to reverse ArrayList contents ?
- Java – Remove duplicate elements from ArrayList
- Java – How to remove duplicate elements of ArrayList maintaining insertion-order ?
References:
- https://docs.oracle.com/javase/tutorial/collections/intro/
- https://docs.oracle.com/javase/tutorial/collections/interfaces/collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Enumeration.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/7/docs/api/java/util/ListIterator.html
Happy Coding !!
Happy Learning !!