The explanation is horribly wrong.
In Java 3 = 12
51–55 of 55 posts
Re: In Java 3 = 12
#52I had to look twice at this. I was surprised that I could add the string “=“ to ‘3’. I guess what’s happening here is the int gets boxed and then gets implicitly converted to String. Proof of the pudding would be to try it with a simple string assignment rather than System.out.println. What happens after the “=“ is more straightforward
This code gives the same result:
String splat = 1 + 2 + " = " + 1 + 2;
System.out.println(splat);
The JLS spec [0] accounts for this in its treatment of the '+' operator:
"If the type of either operand of a + operator is String, then the operation is string concatenation."
This does seem like idiosyncratic behaviour for java to be honest.
I don't think it's the compiler doing it either, because this will throw a null-pointer exception:
Integer borken = null;
String splat = borken + 2 + " = " + 1 + 2;
System.out.println(splat);
Plus.java:8: error: bad operand types for binary operator '+'
String splat = borken + 2 + " = " + 1 + 2;
Re: In Java 3 = 12
#531) Left-associativity 2) The price you pay for type coercion. Be thankful Java defines the order of evaluation. Not all languages which coerce specify the order of evaluation.
I would have expected the compiler / type checker to barf at the example code. Then again, I am not a Java person.
However, I do dislike relying on automatic type coercion anyway, because my intuition is not good at predicting what will happen, and I am too lazy to learn all the rules. ;-)
Re: In Java 3 = 12
#54Earlier quoted context omitted.
> In other words, in python this bug can lurk undetected in your code Well, if you use Python 3 and a modern editor, you will get a big red warning. mypy has been able to check types for a while and a lot of editors embed it.
But mypy is basically a static type checker for python. So my point still stands that static implies that strong-ness is checked at compile time, or IDE time in this case. Thinking about this more, if all that strong vs weak is referring to is implicit type coercions then it is a useless confusing term. Static vs dynamic refers to when the type checking occurs, implicit type coercions are just one of the things the t…
I've always seen the difference as this:
- In statically-typed languages, variables are containers, which allow only objects of a certain type to be contained within.
- In dynamically-typed languages, variables are more like labels which can be attached to different objects, which can be of different types.
Each of these approaches have its merits, which is obvious when you look at all the lengths languages of one type go to to emulate the features of the other: interfaces and generics in statically-typed languages, or type hints and statical checkers in dynamic ones. But I have yet to see a language that would offer both types of variables...
As a Python developer, I can easily imagine a PEP that would introduce some kind of "container variables" that would accept only properly typed objects and throw a syntax error if a violation occurs at compile time. But I'm not holding my breath, with a language which ironically doesn't even have an implementation for constants.
Re: In Java 3 = 12
#55I really don't think this should be confusing - having a decent grasp on associativity and precedence is a pretty useful skill - so for example understanding WHY println(3 * 2 + "-" + 6 * 3) behaves "differently" is something I'd hope people would get. And let's be honest, you definitely don't want to 'fix' this by tweaking precedence to include types. That way madness lies. ;) Definite shout to ubernostrum's commmen…
In Ada the (String) concatenation operator is '&' (and of course, no implicit promotion to String there, you'll have to use your_type'Image(your_var) or with GNAT your_var'Img).