4 ms·

What is the difference between a string and a String? I've written Java for 15 years, and I've never heard of a lowercase-s string before.

johnnyg 14y ago
I scrolled to the comments section of this article looking for exactly that! Do tell!
vanderZwan 14y ago
Maybe somebody named his String variable string?
- pjungwir 14y ago
  I think this is probably it. It's the only thing I can think of.
  - lkrubner 14y ago
    Someone should be shot.
RossM 14y ago
It's been a while since I worked on some Java but I believe it has something to do with one being a type (like int) and the other being an instance of the class String. I was always taught "just use String" but I'd love to know the real difference. Google is not proving fruitful for this question.
vineel 14y ago
Yeah, I don't think "string" is a thing in Java. Maybe he was comparing it to a data type from another language?
- wasd 14y ago
  He might be referring to Integer versus int and Long versus long.
dexen 14y ago
It seems there isn't. There is only one `String' datatype in Java, instance of class String, and no primivite `string' type. String literals represent instances of class String, as per http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.3.3 http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#... Perhaps author meant JavaScript, which does have primitive `string' type, distinct from instances of class `String'?
- deleted 14y ago
  [deleted]
eterm 14y ago
Maybe he's anonymised his experience slightly by subbing Java for C#: C# has a string and a String, although string is just an alias to System.String, so they're really the same. It's not terribly confusing, although syntax highlighters do treat them differently which I could see could confuse the uninitiated.
jakejake 14y ago
Maybe the answer is that String is a class and string has no special meaning in Java? It could be that the author was shown a bit of code where an instance of a String was called string (I've seen this many times as an argument name especially in methods for converting or manipulating a String value). But since the code wasn't mentioned we have no idea, Seems like a nasty trick question to ask of an intern who doesn't know Java!
- pjungwir 14y ago
  I agree if it was asked with no context ("What's the difference between String and string?"), I wouldn't be sure how to answer either! (But in the OP, wasn't it the author who asked the question?) It reminds me of an interview question I was asked once (thought not as bad as String/string): "What is the time complexity to print every node in a binary tree?"
mbrameld 14y ago
You probably know this, but I think the author is confusing a string literal with a lowercase string. String a = "hello"; String b = "hello"; a == b will evaluate to true. String a = new String("hello"); String b = new String("hello"); a == b will evaluate to false. String literals in Java are put in to a string "heap" (might not be the correct word) and reused. Strings objects create a new instance for each string.

johnnyg 14y ago

I scrolled to the comments section of this article looking for exactly that! Do tell!

vanderZwan 14y ago

Maybe somebody named his String variable string?

pjungwir 14y ago
I think this is probably it. It's the only thing I can think of.
- lkrubner 14y ago
  Someone should be shot.

RossM 14y ago

It's been a while since I worked on some Java but I believe it has something to do with one being a type (like int) and the other being an instance of the class String. I was always taught "just use String" but I'd love to know the real difference. Google is not proving fruitful for this question.

vineel 14y ago

Yeah, I don't think "string" is a thing in Java. Maybe he was comparing it to a data type from another language?

wasd 14y ago
He might be referring to Integer versus int and Long versus long.

dexen 14y ago

It seems there isn't. There is only one `String' datatype in Java, instance of class String, and no primivite `string' type. String literals represent instances of class String, as per http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.3.3 http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#... Perhaps author meant JavaScript, which does have primitive `string' type, distinct from instances of class `String'?

deleted 14y ago
[deleted]

eterm 14y ago

Maybe he's anonymised his experience slightly by subbing Java for C#: C# has a string and a String, although string is just an alias to System.String, so they're really the same. It's not terribly confusing, although syntax highlighters do treat them differently which I could see could confuse the uninitiated.

jakejake 14y ago

Maybe the answer is that String is a class and string has no special meaning in Java? It could be that the author was shown a bit of code where an instance of a String was called string (I've seen this many times as an argument name especially in methods for converting or manipulating a String value). But since the code wasn't mentioned we have no idea, Seems like a nasty trick question to ask of an intern who doesn't know Java!

pjungwir 14y ago
I agree if it was asked with no context ("What's the difference between String and string?"), I wouldn't be sure how to answer either! (But in the OP, wasn't it the author who asked the question?) It reminds me of an interview question I was asked once (thought not as bad as String/string): "What is the time complexity to print every node in a binary tree?"

mbrameld 14y ago

You probably know this, but I think the author is confusing a string literal with a lowercase string. String a = "hello"; String b = "hello"; a == b will evaluate to true. String a = new String("hello"); String b = new String("hello"); a == b will evaluate to false. String literals in Java are put in to a string "heap" (might not be the correct word) and reused. Strings objects create a new instance for each string.