arraylist class in java code example

Example 1: how to import an arraylist in java

import java.util.ArrayList;

Example 2: how to create a list in java

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

class scratch{
    public static void main(String[] args) {
        List<Integer> aList = new ArrayList<>();
        List<Integer> lList = new LinkedList<>();
    }
}

Example 3: 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<String> l = new ArrayList<String>();
ArrayList<Integer> a = new ArrayList<Integer>();
//only reference data types allowed in brackets <>

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

Example 4: arraylist java

//requires either one of these two imports, both work.
import java.util.ArrayList;
//--or--
import java.util.*

ArrayList<DataType> name = new ArrayList<DataType>();
//Defining an arraylist, substitute "DataType" with an Object
//such as Integer, Double, String, etc
//the < > is required
//replace "name" with your name for the arraylist

Example 5: arraylist java methds

import java.util.ArrayList;
ArrayList<Integer> myList = new ArrayList<Integer>();
myList.add(0);
myList.remove(0);//Remove at index 0
myList.size();
myList.get(0);//Return element at index 0

Example 6: java arraylist

List<String> expenseTypeList = new ArrayList<>();
        expenseTypeList.add("GENERAL");
        expenseTypeList.add("PURCHASE");
        expenseTypeList.add("PROJECT");