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Resizable Array in Java with ArrayList

java-display

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

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 is a budding programmer, web designer and developer.