ArrayList_Implementation

import java.io.*;
import java.util.*;
public class ArrayListExample {
	public static void main(String args[])throws IOException{
		BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
		ArrayList<Integer> alist=new ArrayList<Integer>();
		System.out.println("Enter 1 to add element");
		System.out.println("Enter 2 to get element");
		System.out.println("Enter 3 to set element");
		boolean condition=true;
		while(condition){
			System.out.println("Enter your choice");
			int ch=Integer.parseInt(in.readLine());
			switch(ch)
			{
			case 1: System.out.println("Enter element to add");
					int element=Integer.parseInt(in.readLine());
					alist.add(element);
					break;
			case 2: System.out.println("Enter element to get");
					int index=Integer.parseInt(in.readLine());
					//gives exception if element at that index is not present
					int value=0;
					if(alist.size()>index)
					value=alist.get(index);
					System.out.println(value);
					break;
			case 3: System.out.println("Enter element to set");
					int index2=Integer.parseInt(in.readLine());
					int updatedValue=Integer.parseInt(in.readLine());
					//will throw an exception if index is greater than arraylist size
					if(index2<alist.size())
					alist.set(index2, updatedValue);
					break;
			case 4: System.out.println("Enter element to remove");
					int val=Integer.parseInt(in.readLine());
					alist.remove(new Integer(val));
					break;
			case 5: System.out.println("Enter index of element to remove");
					int index3=Integer.parseInt(in.readLine());
					//this will throw an IndexOutOfBounds exception if an attempt is made to remove
					//element from an index which is beyond the limits of arraylist
					System.out.println("MAXM SIZE"+alist.size());
					if(alist.size()>index3)
					alist.remove(index3);
					break;
			case 6: Object a[]=alist.toArray();
					Integer b[]=alist.toArray(new Integer[alist.size()]);
					for(int i : b)
					System.out.println(i);
					break;
			case 7: System.out.println(alist);
					break;
			default : condition= false;
					  break;
			}
		}
	}
}