Java try/catch - either "return isn't found" or "variable isn't initialized"?

Question

I've been staring at this for hours and unable to think of a solution; I usually handle validation of this type with regex but am trying to use a built-in solution for a change (obviously, I don't do this frequently):

private static double promptUserDecimal(){
    Scanner scan = new Scanner(System.in);
    System.out.println("Enter a decimal");
    try{
        double input2 = Double.parseDouble(scan.nextLine());
        return input2;
    } catch(NumberFormatException e){
        System.out.println("Sorry, you provided an invalid option, please try again.");
    }
}

The error with this is that the "return" isn't found by the compiler so I get a compile error. If I put the "return" outside of the try/catch I need to declare/initialize "input2" which defeats the purpose of the operation. Any assistance is appreciated...

Answer 1

If you want the user to "please try again", it sounds like you need a loop:

private static double promptUserDecimal(){
    final Scanner scan = new Scanner(System.in);

    // Ask for input until we get something valid
    while (true) {  // Terminated by return within
        System.out.println("Enter a decimal");
        try {
            return Double.parseDouble(scan.nextLine());
        } catch(NumberFormatException e){
            System.out.println("Sorry, you provided an invalid option, please try again.");
            // No return, so the loop will run again
        }
    }
}

Answer 2

You need something like:

double input2;
try{
  //read input2
}catch( ... ){
  //... log AND assign a value to input2 in case of invalid input
}
return input2;

Answer 3

Let your method throw an exception or return nan.

Answer 4

Throw an exception in the catch section. Wherever you call the promptUserDecimal method, catch any exception and print the message there:

public static void main(String[] args) {

    double d = 0.0;
    while (double == 0) {
        try {
            d = promptUserDecimal();
        } catch (NumberFormatException e) {
            //log the message...
            d = 0.0;
        }
    }
}

private static double promptUserDecimal() throws NumberFormatException {
    Scanner scan = new Scanner(System.in);
    System.out.println("Enter a decimal");
    return Double.parseDouble(scan.nextLine());
}

This would be a better approach because you let the promptUserDecimal cares only about handling reading a double value. You must try to tend to separate each class and method for the specific purpose it was designed for.