"variable might not have been initialized" even though I make sure it is

Question

I am having trouble with Javac on compiling this piece of code:

public static int getYear() {
    Console input = System.console();
    Boolean gotYear = false;
    int year;

    String userInput = input.readLine();

    while (!gotYear) {
        try {
            year = Integer.parseInt(userInput);
            gotYear = true;
        } catch (Exception e) {
            System.out.print("Please insert a valid date. ");
            userInput = input.readLine();
        }
    }

    return year;
}

Javac gives me the error on line return year; that "variable 'year' might not have been initialized". But since it's inside a while loop, I know for sure it will have been initialized. I asked my T.A. about this and he was not able to answer me why this happens. His best guess is that Javac is not a very good compiler for figuring this kind of stuff out.

Basically, why is this error happening? I know I can fix it by initializing year before I enter the while loop, but I wanted to know if there is another way of achieving what I'm trying to achieve.

Answer 1

No. You have to initialize. Local aka method variables must gets initialized before they use.

Local variable won't get default values. You have to initialize them, before you use.

Answer 2

Your year variable is initialized in a try block. It's obvious to us that it won't get out the loop until something OK is input. But the compiler's rules are simpler than that : as the initialisation can be disrupted by an exception, it considers that year may be uninitialized.