What is the Java ?: operator called and what does it do?

Question

I have been working with Java a couple of years, but up until recently I haven\'t run across this construct:

int count = isHere ? getHereCount(index) : getAw         


        

Answer 1

Ternary, conditional; tomato, tomatoh. What it's really valuable for is variable initialization. If (like me) you're fond of initializing variables where they are defined, the conditional ternary operator (for it is both) permits you to do that in cases where there is conditionality about its value. Particularly notable in final fields, but useful elsewhere, too.

e.g.:

public class Foo {
    final double    value;

    public Foo(boolean positive, double value) {
        this.value = positive ? value : -value;
    }
}

Without that operator - by whatever name - you would have to make the field non-final or write a function simply to initialize it. Actually, that's not right - it can still be initialized using if/else, at least in Java. But I find this cleaner.