@amanda.hinchman-dominguez What you're talking about is a consequence of how these functions are called in a certain context, but the compiler cannot know that the value has been set before hand 🙂 That's why it refused to compile the code. As Carl pointed out, the typical solution is to assign a negative value, or since you're using JavaFX, you could use IntegerProperty instead, which can contain null, so you can actually check if it was called before hand if needed.