Kann mir jm. eine Lösung nennen um zu verhindern ,dass man ,um die zweite if Bedingung zu erfüllen, keine 2mal "U" als input eingeben muss?
Danke schonmal! 
[code=Java]import java.util.Scanner;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Circle {
public static void main(String[] args) {
System.out.println("Enter your start variable. (A, U, r oder d)");
// define all variables as String
String AS = ("A");
String US = ("U");
String rS = ("r");
String dS = ("d");
Scanner var = new Scanner(System.in);
if(var.next().equals(AS)){
double A = 0;
System.out.println("Please enter area of your circle");
try
{
//get the area from console
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
A = Integer.parseInt(br.readLine());
}
//if invalid value was entered
catch(NumberFormatException ne)
{
System.out.println("Invalid radius value" + ne);
System.exit(0);
}
catch(IOException ioe)
{
System.out.println("IO Error :" + ioe);
System.exit(0);
}
//NOTE : use Math.PI constant to get value of pi
//define all variables
double U = Math.PI * (Math.sqrt(A / Math.PI)) * (Math.sqrt(A / Math.PI));
System.out.println("U = " + U);
double r = Math.sqrt(A / Math.PI);
System.out.println("r = " + r);
double d = (Math.sqrt(A / Math.PI) + (Math.sqrt(A / Math.PI)));
System.out.println("d = " + d);
}
else if (var.next().equals(US)){
double U = 0;
System.out.println("Please enter extent of your circle");
try
{
//get the extent from console
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
U = Integer.parseInt(br.readLine());
}
//if invalid value was entered
catch(NumberFormatException ne)
{
System.out.println("Invalid extent value" + ne);
System.exit(0);
}
catch(IOException ioe)
{
System.out.println("IO Error :" + ioe);
System.exit(0);
}
//NOTE : use Math.PI constant to get value of pi
//define all variables
double A = Math.PI * ((U / (2 * Math.PI) * (U / (2 * Math.PI))));
System.out.println("A = " + A);
double r = U / (2 * Math.PI);
System.out.println("r = " + r);
double d = (U / (2 * Math.PI) + (U / (2 * Math.PI)));
System.out.println("d = " + d);
}
}
}
[/code]
