arraylist

1import java.util.ArrayList;

1import java.util.ArrayList;
2public class ArrayListExample
3{
4   public static void main(String[] args)
5   {
6      int num = 14;
7      // declaring ArrayList with initial size num
8      ArrayList<Integer> al = new ArrayList<Integer>(num);
9      // append new element at the end of list
10      for(int a = 1; a <= num; a++)
11      {
12         al.add(a);
13      }
14      System.out.println(al);
15      // remove element at index 7
16      al.remove(7);
17      // print ArrayList after deletion
18      System.out.println(al);
19      // print elements one by one
20      for(int a = 0; a < al.size(); a++)
21      {
22         System.out.print(al.get(a) + " ");
23      }
24   }
25}

1import java.util.List; //list abstract class
2import java.util.ArrayList; //arraylist class
3
4//Object Lists
5List l = new ArrayList();
6ArrayList a = new ArrayList();
7
8//Specialized List
9List<String> l = new ArrayList<String>();
10ArrayList<Integer> a = new ArrayList<Integer>();
11//only reference data types allowed in brackets <>
12
13//Initial Capacity
14List<Double> l = new ArrayList<Double>(5);
15//list will start with a capacity of 5
16//saves allocation times

1//requires either one of these two imports, both work.
2import java.util.ArrayList;
3//--or--
4import java.util.*
5
6ArrayList<DataType> name = new ArrayList<DataType>();
7//Defining an arraylist, substitute "DataType" with an Object
8//such as Integer, Double, String, etc
9//the < > is required
10//replace "name" with your name for the arraylist

1ArrayList<String>arrayList=new ArrayList<>();

1// THIS IS OKAY:
2ArrayList arrayList = new ArrayList();