Validating data to nest if or not within try and catch

Question

I am validating data, in this case I want one of three ints. I am asking this question, as it is the fundamental principle I'm interested in. This is a basic example, but I am developing best practices now, so when things become more complicated later, I am better equipped to manage them.

Is it preferable to have the try and catch followed by the condition:

public static int getProcType()
{
    try
    {
        procType = getIntInput("Enter procedure type -\n"
            + " 1 for Exploratory,\n" 
            + " 2 for Reconstructive, \n"
            + "3 for Follow up: \n");
    }
    catch (NumberFormatException ex)
    {
        System.out.println("Error! Enter a valid option!");
        getProcType();
    }
    if (procType == 1 || procType == 2 || procType == 3)
    {
        hrlyRate = hrlyRate(procType);
        procedure = procedure(procType);
    }
    else
    {
        System.out.println("Error! Enter a valid option!");
        getProcType();
    }

    return procType;
}

Or is it better to put the if within the try and catch?

public static int getProcType()
{
    try
    {
        procType = getIntInput("Enter procedure type -\n"
            + " 1 for Exploratory,\n" 
            + " 2 for Reconstructive, \n"
            + "3 for Follow up: \n");

        if (procType == 1 || procType == 2 || procType == 3)
        {
            hrlyRate = hrlyRate(procType);
            procedure = procedure(procType);
        }
        else
        {
            System.out.println("Error! Enter a valid option!");
            getProcType();
        }
    }
    catch (NumberFormatException ex)
    {
        System.out.println("Error! Enter a valid option!");
        getProcType();
    }

    return procType;
}

I am thinking the if within the try, may be quicker, but also may be clumsy. Which would be better, as my programming becomes more advanced?

Answer 1

I wouldn't bother using an exception. Instead just a simple test on an IF condition on the method/function.

As @gnat says, putting this in a seprate merthod/function is the best. Also, consider adding an enumeration for the return with an extra value like:

 Exploratory,
 Reconstructive, 
 FollowUp, 
 Undefined

So, when getProcType() is called it can return "Undefined" back. If your program gets that display a message to the user and then quit. If it gets a proper value, it continues and calls another method to call the hourly rate and procedure (separate method).

In your code, how does the user cancel out? They could get stuck trying to enter 1,2,3 as the function keeps calling itself. It usually better to fail fast. So, politely tell the user they entered the wrong value, display a list of acceptable values and then quit. I'm assuming this is some sort of command line utility.

Also, I can suggest using a more sophisticated UI like a list box/combo box which would eliminate having the user typing anything. Then this logic would not be needed at all. In general we want to avoid having the using type in things whenever possible.