LITMIR.BIZ

          /**

           * @param args the command line arguments

           */

          public static void main(String[] args) {

              String answer,symbol;

              float num1=0,num2=0,result=0;

              Scanner sc=new Scanner(System.in);

              do{

              System.out.println("Первое число:");

              try{

              num1=sc.nextFloat();

              }catch(Exception e){

                  System.out.println("Некорректное значение");

                  return;

              }

              Scanner scSymb=new Scanner(System.in);

              System.out.println("Знак:");

              symbol=scSymb.nextLine();

              if(!"+".equals(symbol)&&!"-".equals(symbol)&&!"*".equals(symbol)&&!"/".equals(symbol)){

                  System.out.println("Некорректный символ");

                  return;

              }

              System.out.println("Второе число:");

              try{

              num2=sc.nextFloat();

              }catch(Exception e){

                   System.out.println("Некорректное значение");

                  return;

              }

              switch(symbol){

                  case "+":

                      result=plus(num1, num2);

                      break;

                      case "-":

                          result=minus(num1, num2);

                          break;

                          case "*":

                              result=multiPlus(num1, num2);

                              break;

                              case "/":

                                  result=multiMinus(num1, num2);

                                  break;

                                  default:

                                      break;

              }

              System.out.println(num1+symbol+num2+"="+result);

               Scanner scAns=new Scanner(System.in);

                System.out.println("Начать заново?(д/н)");

              answer=scAns.nextLine();

               if(!"д".equals(answer)&&!"y".equals(answer)){

                  System.out.println("Работа программы завершена");

                  return;

               }

              }while ("д".equals(answer)||"y".equals(answer));

          }

          static float plus(float a,float b){

              return a+b;

          }

          static float multiPlus(float a,float b){

              return a*b;

          }

          static float minus(float a,float b){

              return a-b;

          }

          static float multiMinus(float a,float b){

              return a/b;

          }

      }