Help me with a program

Question

Hello I hope someone can help me!!!!!!!
I have made a program to make math
here it is. now it works but i want to change from "Integer" to "double" , but this don't work my compiler says always error
can someone help me!
when you can please sent me a mail [email protected]
import java.io.*;
public class Summe     {
     public static void main (String argv[]) throws IOException
     String str;
     int a,b,c;
     BufferedReader eingabe = new BufferedReader (new InputStreamReader(System.in));
     System.out.print ("geben sie die erste zahl ein:");
     str = eingabe.readLine();
     a=Integer.parseInt(str);
     System.out.print("geben sie die zweite zahl ein:");
     str = eingabe.readLine();
     b=Integer.parseInt(str);
     c=a+b;
     System.out.println ("Die Summe von " a " und " b " ist: " +c);
     System.out.println ("Programmende Summe.");

Answer 1

import java.io.*;
public class Summe {
public static void main (String argv[]) throws IOException
String str;
double a,b,c;
BufferedReader eingabe = new BufferedReader (new InputStreamReader(System.in));
System.out.print ("geben sie die erste zahl ein:");
str = eingabe.readLine();
a=Double.parseDouble(str);
System.out.print("geben sie die zweite zahl ein:");
str = eingabe.readLine();
b=Double.parseDouble(str);
c=a+b;
System.out.println ("Die Summe von " a " und " b " ist: " +c);
System.out.println ("Programmende Summe.");
And what was the problem, I wonder?