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Resizable Array in Java with ArrayList

May 1, 2017
Published By : Pratik Kataria
Categorised in: Java Core

Understanding through Code

import java.util.List;
import java.util.ArrayList;

public class ArrayListDemo {
	public static void main( String[] args ){

		List<String> list = new ArrayList<>();

		list.add("India");
		list.add("US");
		list.add("Canada");

		System.out.println(list);

		list.add("Russia");
		System.out.println(list);

		list.remove(1);
		System.out.println(list);

		String nation = list.get(0);
		System.out.println("The first nation is: " +nation);

		int pos = list.indexOf("Canada");
		System.out.println("Canada is at: " +pos);

	}
}

Output

• [India, US, Canada]
• [India, US, Canada, Russia]
• [India, Canada, Russia]
• The first nation is: India
• Canada is at: 1

Notes

• Collection framework is a set of interfaces or classes that make management of data easy.
• The two most commonly used frameworks are: ArrayList and HashMap.
• <String> is generic notation or diamond operator. It denotes the list contains what data type
• For integer we have to put helper class: <Integer>
• It is possible to create instance of interface ‘List’ but then we would have to implement all of the methods.
• We have called constructor of ArrayList. We don’t need to pass data type after ArrayList<>.

Pratik Kataria

Pratik Kataria is currently learning Springboot and Hibernate.
Technologies known and worked on: C/C++, Java, Python, JavaScript, HTML, CSS, WordPress, Angular, Ionic, MongoDB, SQL and Android.
Softwares known and worked on: Adobe Photoshop, Adobe Illustrator and Adobe After Effects.

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