Integer toString int i vs String valueOf int i

Question

I am wondering why the method String valueOf int i  exists   I am using this method to convert int into String and just discovered the Integer toString int i  method   After looking the implementation of these methods I saw that the first one is calling the second one  As a consequence all my calls to String valueOf int i  involve one more call than directly calling Integer toString int i

User · Answer

toString      is present in Object class  generally overrided in derived class typecast to appropriate class is necessary to call toString   method    valueOf     Overloaded static method present in String class  handles primitive types as well as object types   Integer a   null  System out println Integer toString      NUll pointer exception System out println String valueOf     give NULL as value    check this link its very good  http   code4reference com 2013 06 which-one-is-better-valueof-or-tostring

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Just two different ways of doing the same thing  It may be a historical reason  can t remember if one came before the other

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The String class provides valueOf methods for all primitive types and Object type so I assume they are convenience methods that can all be accessed through the one class   NB Profiling results  Average intToString   5368ms  Average stringValueOf   5689ms  for 100 000 000 operations   public class StringIntTest         public static long intToString              long startTime   System currentTimeMillis            for  int i   0  i  lt  100000000  i                  String j   Integer toString i                     long finishTime   System currentTimeMillis             return finishTime - startTime             public static long stringValueOf               long startTime   System currentTimeMillis            for  int i   0  i  lt  100000000  i                  String j   String valueOf i                     long finishTime   System currentTimeMillis             return finishTime - startTime             public static void main String   args            long intToStringElapsed   0          long stringValueOfElapsed   0          for  int i   0  i  lt  10  i                  intToStringElapsed    intToString                stringValueOfElapsed   stringValueOf                      System out println  Average intToString       intToStringElapsed  10            System out println  Average stringValueOf       stringValueOfElapsed   10

User · Answer

The implementation of String valueOf   that you see is the simplest way to meet the contract specified in the API   The representation is exactly the one returned by the Integer toString   method of one argument

User · Answer

You shouldn t worry about this extra call costing you efficiency problems  If there s any cost  it ll be minimal  and should be negligible in the bigger picture of things   Perhaps the reason why both exist is to offer readability  In the context of many types being converted to String  then various calls to String valueOf SomeType  may be more readable than various SomeType toString calls

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One huge difference is that if you invoke toString   in a null object you ll get a NullPointerException whereas  using String valueOf   you may not check for null

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From the Java sources         Returns the string representation of the   code int  argument      lt p gt     The representation is exactly the one returned by the      code Integer toString  method of one argument         param   i   an   code int       return  a string representation of the   code int  argument      see     java lang Integer toString int  int      public static String valueOf int i        return Integer toString i      So they give exactly the same result and one in fact calls the other  String valueOf is more flexible if you might change the type later

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Using the method  String valueOf   you do not have to worry about the data whether it is int long char char   boolean Object   you can just call     static String   valueOf     using the only syntax String valueOf   can whatever you pass as a parameter is converted to String and returned    Otherwise  if you use   Integer toString   Float toString   etc  i e  SomeType toString    then you will have to check the datatype of parameter that you want to convert into string  So  its better to use  String valueOf   for such convertions   If you are having an array of object class that contains different values like Integer Char Float etc  then by using  String valueOf   method you can convert the elements of such array into String form easily  On contrary  if you want to use SomeType toString   then at first you will need to know about there their datatype classes maybe by using  instanceOf  operator  and then only you can proceed for a typecast   String valueOf   method when called matches the parameter that is passed whether its Integer Char Float etc   and by using method overloading calls that  valueOf    method whose parameter gets matched  and then inside that method their is a direct call to corresponding  toString    method    So  we can see how the overhead  of checking datatype and then calling corresponding  toString    method is removed Only we need is to call  String valueOf   method  not caring about what we want to convert to String   Conclusion  String valueOf   method has its importance just at cost of one more call

User · Answer

In String type we have several method valueOf  static String   valueOf boolean b   static String   valueOf char c   static String   valueOf char   data   static String   valueOf char   data  int offset  int count   static String   valueOf double d   static String   valueOf float f   static String   valueOf int i   static String   valueOf long l   static String   valueOf Object obj     As we can see those method are capable to resolve all kind of numbers   every implementation of specific method like you have presented  So for integers we have   Integer toString int i    for double   Double toString double d    and so on   In my opinion this is not some historical thing  but it is more useful for a developer to use the method valueOf from the String class than from the proper type  as it leads to fewer changes for us to make    Sample 1   public String doStuff int num          Do something with num       return String valueOf num         Sample2   public String doStuff int num         Do something with num      return Integer toString num         As we see in sample 2 we have to do two changes  in contrary to sample one    In my conclusion  using the valueOf method from String class is more flexible and that s why it is available there

User · Answer

To answer the OPs question  it s simply a helper wrapper to have the other call  and comes down to style choice and that is it   I think there s a lot of misinformation here and the best thing a Java developer can do is look at the implementation for each method  it s one or two clicks away in any IDE   You will clearly see that String valueOf int  is simply calling Integer toString int  for you   Therefore  there is absolutely zero difference  in that they both create a char buffer  walk through the digits in the number  then copy that into a new String and return it  therefore each are creating one String object    Only difference is one extra call  which the compiler eliminates to a single call anyway   So it matters not which you call  other than maybe code-consistency   As to the comments about nulls  it takes a primitive  therefore it can not be null   You will get a compile-time error if you don t initialize the int being passed   So there is no difference in how it handles nulls as they re non-existent in this case

User · Answer

There have no differences between Integer toString 5  and String valueOf 5    because String valueOf returns   public static String valueOf int i        return Integer toString i     public static String valueOf float f        return Float toString f       etc

User · Answer

If you look at the source code for the String class  it actually calls Integer toString   when you call valueOf     That being said  Integer toString   might be a tad faster if the method calls aren t optimized at compile time  which they probably are

User · Answer

my openion is  valueof   always called tostring   for representaion and so for rpresentaion of primtive type valueof is generalized and java by default does not support Data type but it define its work with objaect and class its made all thing in cllas and made object  here  Integer toString int i  create a limit that conversion for only integer

[java] Integer.toString(int i) vs String.valueOf(int i)

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