kalkulatorjava

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author Yuono Edi Setyo (www.kutukuper.com)
 */
@WebServlet(urlPatterns = {"/proses2"})
public class proses2 extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try (PrintWriter out = response.getWriter()) {
           RequestDispatcher redis2;
           String angka01 = request.getParameter("angka1");
           String angka02 = request.getParameter("angka2");
           try{
            float ang1= Float.parseFloat(request.getParameter("angka1"));
            float ang2= Float.parseFloat(request.getParameter("angka2"));
           }catch(Exception e){
               redis2=request.getRequestDispatcher("kalkulator.jsp");
               redis2.include(request, response);
               out.println("Silahkan Masukkan Angka.");
           }
           float ang1= Float.parseFloat(request.getParameter("angka1"));
            float ang2= Float.parseFloat(request.getParameter("angka2"));

            String operasi = request.getParameter("rboperasi");
            if(null != operasi)switch (operasi) {
                   case "1":{
                       float hasil=ang1+ang2;
                       request.setAttribute("hasil", hasil);
                       redis2=request.getRequestDispatcher("kalkulator.jsp");
                       redis2.include(request, response);
                       break;
                       }
                   case "2":{
                       float hasil=ang1-ang2;
                       request.setAttribute("hasil", hasil);
                       redis2=request.getRequestDispatcher("kalkulator.jsp");
                       redis2.include(request, response);
                           break;
                       }
                   case "3":{
                       float hasil=ang1*ang2;
                       request.setAttribute("hasil", hasil);
                       redis2=request.getRequestDispatcher("kalkulator.jsp");
                       redis2.include(request, response);
                           break;
                       }
                   case "4":{
                        if(ang2==0){
                          redis2=request.getRequestDispatcher("kalkulator.jsp");
                          redis2.include(request, response);
                          out.print("Tidak Bisa Diibagi Dengan Nol");
                        } else{
                            float hasil=ang1/ang2;
                       request.setAttribute("hasil", hasil);
                       redis2=request.getRequestDispatcher("kalkulator.jsp");
                       String text="Hasil Pengurangan : ";
                       request.setAttribute("text", text);
                       redis2.include(request, response);
                           break;
                        }
                    }
               }else {
                redis2=request.getRequestDispatcher("kalkulator.jsp");
                redis2.include(request, response);
                out.print("Operasi Aritmatika belum dipilih !!");
            }}
    }