Programación en Java/La clase Vector

import java.io.*; public class programa {

   /** Creates a new instance of programa */
   public static void main( String [] args ) throws IOException {
       int i,n,num,op,a,ndt,x,z,sw,j;
       int v[];
       v=new int[10];
       BufferedReader in= new BufferedReader (new InputStreamReader (System.in) );
       System.out.println ("digite dimension de vector:");
       n = Integer.parseInt (in.readLine());
        for(i=1;i<=n;i++)
       {
           System.out.println("digite un numero:");
           num=Integer.parseInt (in.readLine());
           v[i]=num;
       }
    System.out.println("el vector almacenado:");
    for(i=1;i<=n;i++)
    {
        System.out.println(v[i] + " ");
    }
    do{
        System.out.println("menu principal");
           System.out.println("ingresar nota");
           System.out.println("buscar nota");
           System.out.println("eliminar nota");
           System.out.println("actualizar nota");
           System.out.println("salir");
           System.out.println("digite una opcion:");
           op=Integer.parseInt(in.readLine());
           switch(op){
               case 1:
                   System.out.println("digite cantidad de elementos a insertar:");
           j = Integer.parseInt(in.readLine());
           a=n+j;
           for (i=(n+1);i<=a;i++)
          {
               System.out.println("digite nuevo dato:");
               ndt = Integer.parseInt(in.readLine());
               v [i]=ndt;
           }
          
           for (i=1;i<=a;i++)
          {
                System.out.print(v [ i ] + " ");
          }
                   break;
               case 2:
                    System.out.println("digite dato a buscar:");
           x=Integer.parseInt (in.readLine());
    i=1;
    sw=0;
    while(i<=n && sw==0)
    {
        if(v[i]==x)
        {
            System.out.println("el dato se encontro:");
            System.out.println("en la posicion:" + i);
            sw=1;
        }
        i=i+1;
    }
    if(sw==0)
    {
        System.out.println("el dato no existe:");
    }
                   break;
                   case 3:
                       
                   System.out.println("### eliminar nota ###");
                   break;
                   case 4:
                       System.out.println("digite dato a buscar:");
           x = Integer.parseInt(in.readLine());
           i=1;
           sw=0;
           while(i<=n && sw==0)
           {
               if(v[i]==x)
               { 
                   System.out.println("el dato se encontro:" + i);
                   sw=1;
                   System.out.println("digite nuevo dato");
                   z = Integer.parseInt(in.readLine());
                   v[i]=z;
               }
               i=i+1;
           }
           if(sw==0)
           {
               System.out.println("el dato no existe:");
           }
           for (i=1;i<=n;i++)
           {
               System.out.print(v [ i ] + " ");
           }
                   break;
                   case 5:
                   System.out.println("### salir ###");
                   break;
               default:
                   System.out.println("opcion invalida");
                   break;  
           }
       }while(op!=5);
                   System.out.println("fin del programa");
    }
   }