Conversion program question

Question

I have a JAVA question that may seem foolish, but I just can not figure it out! I have a Celsius to Fahrenheit conversion thing here, and it works, but I want to be intuitive and prompt the user for a second entry after the first conversion is made.
The code I have thus far is this:
import java.io.*;
public class TempConversion {
public static void main (String args[]) {
String input;
boolean badInput;
float tempC, tempF;
tempC = 0;
System.out.print("Enter a temperature in degrees Celsius : ");
do {
try {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
input = in.readLine();
catch(IOException ex) { return;} try {
tempC = Float.valueOf(input).floatValue();
badInput = false;
catch (NumberFormatException ex) {
System.out.println(ex.getMessage() + " is an invalid number\nEnter another number : " );
badInput = true;
} while (badInput);
     tempC = Float.valueOf(input).floatValue();
     tempF = tempC * (9.0F/5.0F) + 32.0F;
System.out.println(" ");
System.out.println(tempC + " degrees Celsius = " + tempF + " degrees Fahrenheit");
Now I know there has to be a simple way to rerun the code after the system.out.println spits out the answer, but i can't figure out how to call the statement again. I played around a bit and was able to actually prompt for a second number, and actually input a number, but after that nothing happened. Any suggestions?
I really appreciate your help. Thanks a bunch!
-Chad

Answer 1

The whole conversion process needs to be in a while loop that asks if they want to convert another temperature at the end. Your input validation loop would be inside that loop, because you still need to validate for each conversion. Here's what I came up with based on your code:
import java.io.*;
public class TempConversion {
     public static void main (String args[]) {
          String input;
          boolean badInput;
          boolean keepGoing = true; // Flags when to stop asking.
          float tempC, tempF;
          tempC = 0;
          do { /* while (keepGoing) */
               do { /* while (banInput) */
                    System.out.println("Enter a temperature in degrees Celsius : ");
                    try {
                         BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
                         input = in.readLine();
                    } catch(IOException ex) { return; }
                    try {
                         tempC = Float.parseFloat(input);
                         badInput = false;
                    } catch (NumberFormatException ex) {
                         System.out.println(ex.getMessage() + " is an invalid number." );
                         badInput = true;
               } while (badInput);
               tempC = Float.valueOf(input).floatValue();
               tempF = tempC * (9.0F/5.0F) + 32.0F;
               System.out.println(" ");
               System.out.println(tempC + " degrees Celsius = " + tempF + " degrees Fahrenheit");
               System.out.println("Convert another temperature?  (Y/N)");
               try {
                    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
                    input = in.readLine();
                    // keepGoing will be false for any input except Y or y
                    keepGoing = input != null && input.equalsIgnoreCase("Y");
               } catch(IOException ex) { return; }
          } while (keepGoing);
}