bom dia, estou iniciamdo em programação java, alguem pode me ajuda ?????

import java.util.Scanner;

	import java.lang.AbstractMethodError;

	public class  {

	    public static void main (String[] args){

	        int num1 = 0, num2 = 0; int num = 0;

	        float s, raiz;

	        String numero []= new String [3];

	        float menu [][]= new float [3][3];

	            Scanner entrada = new Scanner(System.in);

	            int op = 0;

	            while (op!= 3){

	                System.out.println(" SISTEMA DE CADASTRO");

	                System.out.println(" 1- Soma");

	                System.out.println(" 2- Raiz Quadrada");

	                System.out.println(" 3- Finalizar");

	                op= entrada.nextInt();

	                switch (op){

	                    case 1: System.out.println (" MENU SOMA...");

	                    System.out.println("1- numero 1"+ num1);

	                    System.out.println("2- numero 2" + num2);

	                    System.out.println("3- Sair");

	                    System.out.println("Escolha uma Opção");

	                    op = entrada.nextInt();

	                    switch (op){

	                        case 1: for (int i = 0; i<3; i++){

	                           s= num1 + num2;

	                           numero [1]= entrada.next();

	                        }

	                        break;

	                        case 2: for (int i = 0; i<3; i++){

	                           s= num1 + num2;

	                           numero [1]= entrada.next();

	                    }

	                        break;

	                        case 3:

	                            System.out.println("saindo do menu Soma");

	                }

	                    break;

	                    case 2 : System.out.println( "Menu Raiz Quadrada...");

	                    System.out.println("1- numero "+num1);

	                    System.out.println("2- numero " + num2);

	                    System.out.println("3- Sair");

	                    System.out.println("Escolha uma Opção");

	                      op = entrada.nextInt();

	                    switch (op){

	                        case 1: for (int i= 0; i<3; i++){  

	                        raiz = math.sqrt(num);

	                        System.out.println(math.sqrt(num));

	                        numero [1]= entrada.next();

	                    }

	                        break;

	                        case 2:  for (int i= 0; i<3; i++){  

	                        raiz = math.sqrt(num);

	                        System.out.println(math.sqrt(num));

	                        numero [1]= entrada.next();

	                        }

	                         break;

	                        case 3:

	                            System.out.println("saindo do menu Raiz Quadrada");

	                }

	                    break;

	                    case 3:

	                        System.out.println(" Finalizando");

	                        break;

	                    default: System.out.println("Comando inválido! Tente novamente!");

	                    break;

	            }

	 }

	    }

	}