Java conditional operator ?: result type

Question

I\'m a bit puzzled about the conditional operator. Consider the following two lines:

Float f1 = false? 1.0f: null;
Float f2 = false? 1.0f: false? 1.0f: null;         


        

Answer 1

I think rewriting the code makes the explanation clearer:

    float f = 1.0f;

    Float null_Float  = false?        f  : null;       // float + null  -> OK
    Float null_Float2 = false? (Float)f  : null_Float; // Float + Float -> OK
    Float npe         = false?        f  : null_Float; // float + Float -> NPE

Thus the NPE is when we try to do something like:

Float npe = false? 1.0f : (Float)null;