Java program to implement ArrayList.

import java.util.Arrays;




public class MyArrayList {




    private Object[] myStore;

    private int actSize = 0;

     

    public MyArrayList(){

        myStore
= new Object[10];

    }

     

    public Object get(int index){

        if(index
< actSize){

            return myStore[index];

        } else {

            throw new ArrayIndexOutOfBoundsException();

        }

    }

     

    public void add(Object obj){

        if(myStore.length-actSize
<= 5){

            increaseListSize();

        }

        myStore[actSize++]
= obj;

    }

     

    public Object remove(int index){

        if(index
< actSize){

            Object
obj = myStore[index];

            myStore[index]
= null;

            int tmp = index;

            while(tmp
< actSize){

                myStore[tmp]
= myStore[tmp+1];

                myStore[tmp+1]
= null;

                tmp++;

            }

            actSize--;

            return obj;

        } else {

            throw new ArrayIndexOutOfBoundsException();

        }

         

    }

     

    public int size(){

        return actSize;

    }

     

    private void increaseListSize(){

        myStore
= Arrays.copyOf(myStore, myStore.length*2);

        System.out.println("\nNew
length: "+myStore.length);

    }

     

    public static void main(String a[]){

        MyArrayList
mal = new MyArrayList();

        mal.add(new Integer(2));

        mal.add(new Integer(5));

        mal.add(new Integer(1));

        mal.add(new Integer(23));

        mal.add(new Integer(14));

        for(int i=0;i<mal.size();i++){

            System.out.print(mal.get(i)+"
");

        }

        mal.add(new Integer(29));

        System.out.println("Element
at Index 5:"+mal.get(5));

        System.out.println("List
size: "+mal.size());

        System.out.println("Removing
element at index 2: "+mal.remove(2));

        for(int i=0;i<mal.size();i++){

            System.out.print(mal.get(i)+"
");

        }

    }

}

Output:

2 5 1 23 14 

New length: 20

Element at Index 5:29

List size: 6

Removing element at index 2: 1

2 5 23 14 29