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

[michel valente 0]

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;
            }
 }
    }
}