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Java Forum / General / March 2008Create String from char - so difficult??
Hello, How to create new String having one char. Is it really only way to create new char array that has length one and using it create string? char a = 'a'; String ss = new String ( new char[] {a}); By the way, in first line characters '' represents only char or it might be something else? As i understood "" always represents String. Thank You > Hello, > [quoted text clipped - 6 lines] > By the way, in first line characters '' represents only char or it > might be something else? As i understood "" always represents String. Any of the following will work. String s = "a"; String s = "" + 'a'; char c = 'a'; String s = "" + c; > String s = "" + 'a'; > > char c = 'a'; > String s = "" + c; "" + i not good code style. Arne >> String s = "" + 'a'; >> [quoted text clipped - 4 lines] > > i[s] not good code style. True. Lothar explained why and suggested char c = 'a'; ... s = Character.toString(c); Perhaps Character c = 'a'; ... String s = c.toString(); would often be marginally preferable? On Mar 22, 4:04 pm, RedGrittyBrick <RedGrittyBr...@SpamWeary.foo> wrote: > >> String s = "" + 'a'; > [quoted text clipped - 15 lines] > String s = c.toString(); > would often be marginally preferable? For almost entirely superstitious reasons I would prefer the former over the latter, even though the latter is more uniform with respect to other, non-primitive types. I dislike intentionally obscuring the line between primitives and non-primitives in Java almost as much as I dislike the existence of primitive, non-reference types in Java in the first place. > How to create new String having one char. Is it really only way to > create new char array that has length one and using it create string? > > char a = 'a'; > String ss = new String ( new char[] {a}); String ss = Character.toString('a'); alternatively String ss = String.valueOf('a'); This way is to be preferred over the usual answer String ss = "" + 'a'; Reason for this is the way Strings are working in Java and what the Java-compiler creates out of that line: String ss = new StringBuffer().append("").append(String.valueOf('a')).toString(); Regards, Lothar  SignatureLothar Kimmeringer E-Mail: spamfang@kimmeringer.de PGP-encrypted mails preferred (Key-ID: 0x8BC3CD81) Always remember: The answer is forty-two, there can only be wrong questions! > char a = 'a'; > String ss = new String ( new char[] {a}); see http://mindprod.com/applet/converter.html SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >How to create new String having one char. Is it really only way to >create new char array that has length one and using it create string? Surely somebody has had it up to here with the irregularity of Java conversion functions and written a wrapper class to convert any primitive to any other (plus strings). like this double Cvt.todouble( String s ); float Cvt.tofloat ( int i ); Float Cvt.toFloat ( long l ); .... See http://mindprod.com/applet/converter.html for the code to implement each function. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >> How to create new String having one char. Is it really only way to >> create new char array that has length one and using it create string? [quoted text clipped - 8 lines] > float Cvt.tofloat ( int i ); > Float Cvt.toFloat ( long l ); I understand why you did it, but the lack of camel case is jarring (no pun intended). Besides, with autoboxing you don't need two versions: float f = Cvt.toFloat( int i ); Float fc = Cvt.toFloat( int i ); Then again, float f = i; works just fine. As for String conversions, I don't understand what you mean by the "irregularity" at all. The String class has valueOf() overloads for all the primitive types. The primitive type wrapper classes except Character have valueOf( String ) overloads. It's hard to be more regular than that, unless you insist on "remedying" the sole exception of Character, and I suspect that one is due to the special relationship between Strings and chars and the existence of String.charAt(). It's not worth running around Jericho's barn to wind up where I'm already standing. SignatureLew >> double Cvt.todouble( String s ); >> float Cvt.tofloat ( int i ); >> Float Cvt.toFloat ( long l ); > float f = Cvt.toFloat( int i ); > Float fc = Cvt.toFloat( int i ); I don't find either of these to be all that readable. In Roedy's example, just the change in case is easy for my old eyes to miss. In your case, overloading functions always runs the risk of calling the wrong function on accident. (Say if the compiler is the one choosing which function to call, how certain are you it calls the one you thought it would?) I think I'd make the function name more explicit, and skip the overloading. float f = Cvt.toPrimitiveFloat( int i ); Float f2 = Cvt.toFloat( int i ); Or something like that. The idea of readability is key here. > >> double Cvt.todouble( String s ); > >> float Cvt.tofloat ( int i ); [quoted text clipped - 9 lines] > which function to call, how certain are you it calls the one you thought > it would?) The whole point of Lew's post is that there is no overloading, as the language already provides a feature that obviates the need for it. In this case, there is a single method public static float toFloat (int i) In the second case, the returned float is being automatically boxed to a Float by the compiler, freeing the programmer from having to write a second method. (Futhermore, Java forbids programmers from overloading by return type only...) -o > (Futhermore, Java forbids programmers from overloading by return type > only...) Oh, good point. I didn't realize that. >Then again, > > float f = i; > >works just fine. that's the problem. the lack of predictability and regularity. You need something a newbie can use mindlessly. A decent optimiser should inline them all so the final code would be just that. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >> Then again, >> [quoted text clipped - 5 lines] > need something a newbie can use mindlessly. A decent optimiser > should inline them all so the final code would be just that. Neither newbies nor roedies[*] should be encouraged to write code mindlessly. [*] Needed a word connoting uncommon breadth and depth of experience, the opposite of "newbie." For the sake of sentence punch, wanted a two-syllable word ending in "-ies" to highlight the contrast; this was the best I could find. SignatureEric.Sosman@sun.com >> Then again, >> [quoted text clipped - 5 lines] > need something a newbie can use mindlessly. A decent optimiser > should inline them all so the final code would be just that. You're on the road to reinventing PL/I. SignatureJohn W. Kennedy "Only an idiot fights a war on two fronts. Only the heir to the throne of the kingdom of idiots would fight a war on twelve fronts" -- J. Michael Straczynski. "Babylon 5", "Ceremonies of Light and Dark" >As for String conversions, I don't understand what you mean by the >"irregularity" at all. The String class has valueOf() overloads for all the [quoted text clipped - 3 lines] >one is due to the special relationship between Strings and chars and the >existence of String.charAt(). have a look at all the various conversions at http://mindprod.com/applet/converter.html There are pockets of regularity, but overall it drives newbies to distraction. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com >I understand why you did it, but the lack of camel case is jarring (no pun >intended). Besides, with autoboxing you don't need two versions: > > float f = Cvt.toFloat( int i ); > Float fc = Cvt.toFloat( int i ); you can't quite to do that e.g. boolean isBig = ctv.toFloat( i ).isInfinite(); I don't think autoboxing would be smart enough to handle that. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com > Float Cvt.toFloat ( long l ); Lew wrote, >> Besides, with autoboxing you don't need two versions: >> >> float f = Cvt.toFloat( i ); >> Float fc = Cvt.toFloat( i ); > you can't quite to do that e.g. > > boolean isBig = ctv.toFloat( i ).isInfinite(); > > I don't think autoboxing would be smart enough to handle that. Works fine here: package testit; public class Boxer { public static Float toFloat( int in ) { return (float) in; } public static Float toFloat( long in ) { return (float) in; } public static void main(String[] args) { int in = 17; boolean isBig = toFloat( in ).isInfinite(); System.out.println( "Is "+ in +" big? "+ isBig ); long ln = 4000000000L; isBig = toFloat( ln ).isInfinite(); System.out.println( "Is "+ ln +" big? "+ isBig ); } } SignatureLew > isBig = toFloat( ln ).isInfinite(); Good. that gets rid of the need to distinguish between toFloat and tofloat. SignatureRoedy Green Canadian Mind Products The Java Glossary http://mindprod.com Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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