ArrayList jav code example

Example 1: java arraylist

import java.util.List; //list abstract class
import java.util.ArrayList; //arraylist class

//Object Lists
List l = new ArrayList();
ArrayList a = new ArrayList();

//Specialized List
List l = new ArrayList();
ArrayList a = new ArrayList();
//only reference data types allowed in brackets <>

//Initial Capacity
List l = new ArrayList(5);
//list will start with a capacity of 5
//saves allocation times

Example 2: arraylist of arraylist

public static void main(String[] args) {
    ArrayList> outer = new ArrayList>();
    ArrayList inner = new ArrayList();        

    inner.add(100);     
    inner.add(200);
    outer.add(inner); // add first list
    inner = new ArrayList(inner); // create a new inner list that has the same content as  
                                           // the original inner list
    outer.add(inner); // add second list

    outer.get(0).add(300); // changes only the first inner list

    System.out.println(outer);
}