Is it possible to define a variable only once without using final

Question

I was wondering if there is a way, in Java, to assign a variable only once. I know there is the final keyword but I would like to achieve same result without having to set the value in the constructor. I want to set it outside the constructor, because I don't know the value yet.

Answer 1

You might need check the key before assigning the value, for example:

Object key;


public void setValue(Object value) {
    if (key != null) {
        // ignore or throw exception, depending on your business logic
    } else {
        key = value;
    } 
}