5 ms·

Ehh, I don't really think this is a huge deal personally. Keep in mind that it is not that `(string)null` gives you the "null" string, or `((string)null).ToStri

by DSMan195276 9y ago

Ehh, I don't really think this is a huge deal personally. Keep in mind that it is not that `(string)null` gives you the "null" string, or `((string)null).ToString()` gives you the null string. You have to use actual string concatenation to get it (Or as others have pointed out, `String.ToValue(null)`). Point being, it isn't/shouldn't be messing up your regular comparisons (Unless you turn it into a string beforehand), and you really shouldn't be checking for stuff like `null` against a string literal anyway - it's meant for displaying a human readable string, not an unambiguous string that could be converted back at a later time. If you wanted that then you should use proper serialization techniques rather then just concatenating a bunch of values.

Zak 9y ago
It's insane in that Java pretends to have strong, static typing, then does things like that.
- Spivak 9y ago
  Overloading the plus operator for strings was probably a mistake in the language but that's hardly a condemnation of their type system.
  - Zak 9y ago
    A lot of languages overload + to mean concatenate. I think that's a mistake, however... In Python: "abc" + None TypeError: cannot concatenate 'str' and 'NoneType' objects "abc".join(None) TypeError: can only join an iterable In Ruby "abc" + nil TypeError: no implicit conversion of nil into String In Lua = "abc" .. Nil attempt to concatenate global 'Nil' (a nil value) But not Java. Java implicitly tries to coerce the provided value to be a string, which seems out of place in a language that values type safety. That all types might also be null also seems out of place in a language with strong, static typing, but that's been discussed to death. The problem is compounded by the fact that null is actually converted to "null" instead of an empty string.
    - Too 9y ago
      On the other hand, it's easier to get into this situation in Python than Java. bar = "bar" foo = "foo" foo_bar = foo + baar # intentional typo (baar will be None) In Java this would be a compiler error, but python accepts it until the program is being run.
      - Zak 9y ago
        That's a NameError in Python: undefined variables don't have a value, not even None. It won't be caught until runtime since there's no AOT compiler in Python, but it's the same kind of error it is in Java. My claim isn't that Python is safer overall than Java. Instead, it's that Java, a language that is mostly type safe, most of the time should not have these two potentially surprising behaviors: 1. The standard string concatenation operator does implicit coercion rather than rejecting an input that isn't a string. There should be a builtin to make a string from any value no matter what for logging and debugging, but that shouldn't be the standard concatenation operator. 2. This is more controversial, but strongly statically typed languages should not allow arbitrary values to be null. That sabotages one of the major strengths of strong static typing. Instead, there should be an option type to make it explicit. For something familiar to most programmers, SQL does this.
ufmace 9y ago
It's not that it's really that huge of a deal, just that it's so out of character for Java and everything it is seen as. It's like if a guy you were friends with since college and always knew to be solid and reliable but a little boring, and now many years later, he's happily married with kids, watching sports, working in a large hierarchical organization, doing pretty average stuff but nothing unusual or exciting. If you suddenly found out that guy had secretly been a Furry the whole time, that would be really shocking. Not that there's anything wrong with being boring and reliable, or being a furry. But the sudden change in how you saw somebody or something is stunning. I half expect anything written in Java to be littered with AbstractFactoryFactories and giant frameworks using 20 different design patterns to write Hello World. I never would have expected Java to silently convert an actual null to the string "null". I always thought the one thing you can count on Java for was to be strictly strongly typed, and never silently do any weird random conversions that nobody would have expected. Guess I was wrong. Though poking around in a few other languages, JavaScript does indeed do that also, though I kinda expect JavaScript to do things like that. In Ruby, nil.to_s gives empty string, and adding a nil to a string gives you a type error. In Python, trying to add None to a string also gives you a type error, but str(None) does give you 'None'. That's a bit disappointing, but not shocking to me.

Zak 9y ago

It's insane in that Java pretends to have strong, static typing, then does things like that.

Spivak 9y ago
Overloading the plus operator for strings was probably a mistake in the language but that's hardly a condemnation of their type system.
- Zak 9y ago
  A lot of languages overload + to mean concatenate. I think that's a mistake, however... In Python: "abc" + None TypeError: cannot concatenate 'str' and 'NoneType' objects "abc".join(None) TypeError: can only join an iterable In Ruby "abc" + nil TypeError: no implicit conversion of nil into String In Lua = "abc" .. Nil attempt to concatenate global 'Nil' (a nil value) But not Java. Java implicitly tries to coerce the provided value to be a string, which seems out of place in a language that values type safety. That all types might also be null also seems out of place in a language with strong, static typing, but that's been discussed to death. The problem is compounded by the fact that null is actually converted to "null" instead of an empty string.
  - Too 9y ago
    On the other hand, it's easier to get into this situation in Python than Java. bar = "bar" foo = "foo" foo_bar = foo + baar # intentional typo (baar will be None) In Java this would be a compiler error, but python accepts it until the program is being run.
    - Zak 9y ago
      That's a NameError in Python: undefined variables don't have a value, not even None. It won't be caught until runtime since there's no AOT compiler in Python, but it's the same kind of error it is in Java. My claim isn't that Python is safer overall than Java. Instead, it's that Java, a language that is mostly type safe, most of the time should not have these two potentially surprising behaviors: 1. The standard string concatenation operator does implicit coercion rather than rejecting an input that isn't a string. There should be a builtin to make a string from any value no matter what for logging and debugging, but that shouldn't be the standard concatenation operator. 2. This is more controversial, but strongly statically typed languages should not allow arbitrary values to be null. That sabotages one of the major strengths of strong static typing. Instead, there should be an option type to make it explicit. For something familiar to most programmers, SQL does this.

ufmace 9y ago

It's not that it's really that huge of a deal, just that it's so out of character for Java and everything it is seen as. It's like if a guy you were friends with since college and always knew to be solid and reliable but a little boring, and now many years later, he's happily married with kids, watching sports, working in a large hierarchical organization, doing pretty average stuff but nothing unusual or exciting. If you suddenly found out that guy had secretly been a Furry the whole time, that would be really shocking. Not that there's anything wrong with being boring and reliable, or being a furry. But the sudden change in how you saw somebody or something is stunning. I half expect anything written in Java to be littered with AbstractFactoryFactories and giant frameworks using 20 different design patterns to write Hello World. I never would have expected Java to silently convert an actual null to the string "null". I always thought the one thing you can count on Java for was to be strictly strongly typed, and never silently do any weird random conversions that nobody would have expected. Guess I was wrong. Though poking around in a few other languages, JavaScript does indeed do that also, though I kinda expect JavaScript to do things like that. In Ruby, nil.to_s gives empty string, and adding a nil to a string gives you a type error. In Python, trying to add None to a string also gives you a type error, but str(None) does give you 'None'. That's a bit disappointing, but not shocking to me.