Different between parseInt and valueOf in java

Question

How is parseInt   different from valueOf       They appear to do exactly the same thing to me  also goes for parseFloat    parseDouble    parseLong   etc  how are they different from Long valueOf string     Also  which one of these is preferable and used more often by convention

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Look at Java sources  valueOf is using parseInt           Parses the specified string as a signed decimal integer value         param string               the string representation of an integer value      return an   code Integer  instance containing the integer value            represented by   code string       throws NumberFormatException                if   code string  cannot be parsed as an integer value      see  parseInt String      public static Integer valueOf String string  throws NumberFormatException       return valueOf parseInt string        parseInt returns int         Parses the specified string as a signed decimal integer value  The ASCII    character  u002d   -   is recognized as the minus sign         param string               the string representation of an integer value      return the primitive integer value represented by   code string       throws NumberFormatException                if   code string  cannot be parsed as an integer value      public static int parseInt String string  throws NumberFormatException       return parseInt string  10

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The parse  variations return primitive types and the valueOf versions return Objects  I believe the valueOf versions will also use an internal reference pool to return the SAME object for a given value  not just another instance with the same internal value

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Integer parseInt can just return int as native type   Integer valueOf may actually need to allocate an Integer object  unless that integer happens to be one of the preallocated ones  This costs more   If you need just native type  use parseInt  If you need an object  use valueOf   Also  because of this potential allocation  autoboxing isn t actually good thing in every way  It can slow down things

User · Answer

Integer parseInt can just return int as native type   Integer valueOf may actually need to allocate an Integer object  unless that integer happens to be one of the preallocated ones  This costs more   If you need just native type  use parseInt  If you need an object  use valueOf   Also  because of this potential allocation  autoboxing isn t actually good thing in every way  It can slow down things

User · Answer

In case of ValueOf -  it is creating an Integer object  not a primitive type and not a static method  In case of ParseInt ParseFloat -  it return respective primitive type  and is a static method     We should use any one depending upon our need  In case of ValueOf as it is instantiating an object  it will consume more resources if we only need value of some text then we should use parseInt parseFloat etc

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From this forum      parseInt   returns primitive integer   type  int   whereby valueOf returns   java lang Integer  which is the object   representative of the integer  There   are circumstances where you might want   an Integer object  instead of   primitive type       Of course  another obvious difference   is that intValue is an instance method   whereby parseInt is a static method

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If you check the Integer class you will find that valueof call parseInt method  The big difference is caching when you call valueof API   It cache if the value is between -128 to 127 Please find below the link for more information  http   docs oracle com javase 7 docs api java lang Integer html

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If you check the Integer class you will find that valueof call parseInt method  The big difference is caching when you call valueof API   It cache if the value is between -128 to 127 Please find below the link for more information  http   docs oracle com javase 7 docs api java lang Integer html

User · Answer

Integer valueOf s    is similar to  new Integer Integer parseInt s     The difference is valueOf   returns an Integer  and parseInt   returns an int  a primitive type   Also note that valueOf   can return a cached Integer instance  which can cause confusing results where the result of    tests seem intermittently correct   Before autoboxing there could be a difference in convenience  after java 1 5 it doesn t really matter   Moreover  Integer parseInt s  can take primitive datatype as well

User · Answer

The parse  variations return primitive types and the valueOf versions return Objects  I believe the valueOf versions will also use an internal reference pool to return the SAME object for a given value  not just another instance with the same internal value

User · Answer

valueOf - converts to Wrapper class parseInt - converts to primitive type   Integer parseInt accept only String and return primitive integer type  int       public static int parseInt String s  throws NumberFormatException           return parseInt s 10           Iteger valueOf accept int and String   If value is String  valueOf convert it to the the simple int using parseInt and return new Integer if input is less than -128 or greater than 127   If input is in range  -128 - 127  it always return the Integer objects from an internal IntegerCache  Integer class maintains an inner static IntegerCache class which acts as the cache and holds integer objects from -128 to 127 and that   s why when we try to get integer object for 127  for example  we always get the same object   Iteger valueOf 200  will give new Integer from 200  It s like new Integer 200   Iteger valueOf 127  is the same as Integer   127   If you wont to convert String to the Integer use Iteger valueOf    If you wont to convert String to the simple int use Integer parseInt  It works faster     public static Integer valueOf int i            if  i  gt   IntegerCache low  amp  amp  i  lt   IntegerCache high              return IntegerCache cache i    -IntegerCache low            return new Integer i            public static Integer valueOf String s  throws NumberFormatException           return Integer valueOf parseInt s  10           private static class IntegerCache         static final int low   -128        static final int high        static final Integer cache         static              high value may be configured by property         int h   127          String integerCacheHighPropValue               sun misc VM getSavedProperty  java lang Integer IntegerCache high            if  integerCacheHighPropValue    null                try                   int i   parseInt integerCacheHighPropValue                   i   Math max i  127                      Maximum array size is Integer MAX VALUE                 h   Math min i  Integer MAX VALUE -  -low  -1                 catch  NumberFormatException nfe                       If the property cannot be parsed into an int  ignore it                                  high   h           cache   new Integer  high - low    1           int j   low          for int k   0  k  lt  cache length  k                cache k    new Integer j                 range  -128  127  must be interned  JLS7 5 1 7          assert IntegerCache high  gt   127             private IntegerCache            And comparing Integer valueOf 127     Integer valueOf 127  return true  Integer a   127     Compiler converts this line to Integer a   Integer valueOf 127   Integer b   127     Compiler converts this line to Integer b   Integer valueOf 127   a    b     return true    Because it takes the Integer objects with the same references from the cache   But Integer valueOf 128     Integer valueOf 128  is false  because 128 is out of IntegerCache range and it return new Integer  so objects will have different references

User · Answer

Look at Java sources  valueOf is using parseInt           Parses the specified string as a signed decimal integer value         param string               the string representation of an integer value      return an   code Integer  instance containing the integer value            represented by   code string       throws NumberFormatException                if   code string  cannot be parsed as an integer value      see  parseInt String      public static Integer valueOf String string  throws NumberFormatException       return valueOf parseInt string        parseInt returns int         Parses the specified string as a signed decimal integer value  The ASCII    character  u002d   -   is recognized as the minus sign         param string               the string representation of an integer value      return the primitive integer value represented by   code string       throws NumberFormatException                if   code string  cannot be parsed as an integer value      public static int parseInt String string  throws NumberFormatException       return parseInt string  10

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Integer parseInt can just return int as native type   Integer valueOf may actually need to allocate an Integer object  unless that integer happens to be one of the preallocated ones  This costs more   If you need just native type  use parseInt  If you need an object  use valueOf   Also  because of this potential allocation  autoboxing isn t actually good thing in every way  It can slow down things

User · Answer

Well  the API for Integer valueOf String  does indeed say that the String is interpreted exactly as if it were given to Integer parseInt String   However  valueOf String  returns a new Integer   object whereas parseInt String  returns a primitive int    If you want to enjoy the potential caching benefits of Integer valueOf int   you could also use this eyesore   Integer k   Integer valueOf Integer parseInt  123      Now  if what you want is the object and not the primitive  then using valueOf String  may be more attractive than making a new object out of parseInt String  because the former is consistently present across Integer  Long  Double  etc

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public static Integer valueOf String s    The argument is interpreted as representing a signed decimal integer  exactly as if the argument were given to the parseInt java lang String  method   The result is an Integer object that represents the integer value specified by the string  In other words  this method returns an Integer object equal to the value of  new Integer Integer parseInt s

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public static Integer valueOf String s    The argument is interpreted as representing a signed decimal integer  exactly as if the argument were given to the parseInt java lang String  method   The result is an Integer object that represents the integer value specified by the string  In other words  this method returns an Integer object equal to the value of  new Integer Integer parseInt s

User · Answer

In case of ValueOf -  it is creating an Integer object  not a primitive type and not a static method  In case of ParseInt ParseFloat -  it return respective primitive type  and is a static method     We should use any one depending upon our need  In case of ValueOf as it is instantiating an object  it will consume more resources if we only need value of some text then we should use parseInt parseFloat etc

User · Answer

From this forum      parseInt   returns primitive integer   type  int   whereby valueOf returns   java lang Integer  which is the object   representative of the integer  There   are circumstances where you might want   an Integer object  instead of   primitive type       Of course  another obvious difference   is that intValue is an instance method   whereby parseInt is a static method

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Because you might be using jdk1 5  and there it is auto converting to int  So in your code its first returning Integer and then auto converted to int   your code is same as   int abc   new Integer 123

User · Answer

The parse  variations return primitive types and the valueOf versions return Objects  I believe the valueOf versions will also use an internal reference pool to return the SAME object for a given value  not just another instance with the same internal value

User · Answer

The parse  variations return primitive types and the valueOf versions return Objects  I believe the valueOf versions will also use an internal reference pool to return the SAME object for a given value  not just another instance with the same internal value

User · Answer

From this forum      parseInt   returns primitive integer   type  int   whereby valueOf returns   java lang Integer  which is the object   representative of the integer  There   are circumstances where you might want   an Integer object  instead of   primitive type       Of course  another obvious difference   is that intValue is an instance method   whereby parseInt is a static method

User · Answer

Well  the API for Integer valueOf String  does indeed say that the String is interpreted exactly as if it were given to Integer parseInt String   However  valueOf String  returns a new Integer   object whereas parseInt String  returns a primitive int    If you want to enjoy the potential caching benefits of Integer valueOf int   you could also use this eyesore   Integer k   Integer valueOf Integer parseInt  123      Now  if what you want is the object and not the primitive  then using valueOf String  may be more attractive than making a new object out of parseInt String  because the former is consistently present across Integer  Long  Double  etc

User · Answer

Because you might be using jdk1 5  and there it is auto converting to int  So in your code its first returning Integer and then auto converted to int   your code is same as   int abc   new Integer 123

User · Answer

Integer valueOf s    is similar to  new Integer Integer parseInt s     The difference is valueOf   returns an Integer  and parseInt   returns an int  a primitive type   Also note that valueOf   can return a cached Integer instance  which can cause confusing results where the result of    tests seem intermittently correct   Before autoboxing there could be a difference in convenience  after java 1 5 it doesn t really matter   Moreover  Integer parseInt s  can take primitive datatype as well

User · Answer

Well  the API for Integer valueOf String  does indeed say that the String is interpreted exactly as if it were given to Integer parseInt String   However  valueOf String  returns a new Integer   object whereas parseInt String  returns a primitive int    If you want to enjoy the potential caching benefits of Integer valueOf int   you could also use this eyesore   Integer k   Integer valueOf Integer parseInt  123      Now  if what you want is the object and not the primitive  then using valueOf String  may be more attractive than making a new object out of parseInt String  because the former is consistently present across Integer  Long  Double  etc

User · Answer

Integer parseInt can just return int as native type   Integer valueOf may actually need to allocate an Integer object  unless that integer happens to be one of the preallocated ones  This costs more   If you need just native type  use parseInt  If you need an object  use valueOf   Also  because of this potential allocation  autoboxing isn t actually good thing in every way  It can slow down things

User · Answer

Integer valueOf s    is similar to  new Integer Integer parseInt s     The difference is valueOf   returns an Integer  and parseInt   returns an int  a primitive type   Also note that valueOf   can return a cached Integer instance  which can cause confusing results where the result of    tests seem intermittently correct   Before autoboxing there could be a difference in convenience  after java 1 5 it doesn t really matter   Moreover  Integer parseInt s  can take primitive datatype as well

User · Answer

Integer valueOf s    is similar to  new Integer Integer parseInt s     The difference is valueOf   returns an Integer  and parseInt   returns an int  a primitive type   Also note that valueOf   can return a cached Integer instance  which can cause confusing results where the result of    tests seem intermittently correct   Before autoboxing there could be a difference in convenience  after java 1 5 it doesn t really matter   Moreover  Integer parseInt s  can take primitive datatype as well

User · Answer

valueOf - converts to Wrapper class parseInt - converts to primitive type   Integer parseInt accept only String and return primitive integer type  int       public static int parseInt String s  throws NumberFormatException           return parseInt s 10           Iteger valueOf accept int and String   If value is String  valueOf convert it to the the simple int using parseInt and return new Integer if input is less than -128 or greater than 127   If input is in range  -128 - 127  it always return the Integer objects from an internal IntegerCache  Integer class maintains an inner static IntegerCache class which acts as the cache and holds integer objects from -128 to 127 and that   s why when we try to get integer object for 127  for example  we always get the same object   Iteger valueOf 200  will give new Integer from 200  It s like new Integer 200   Iteger valueOf 127  is the same as Integer   127   If you wont to convert String to the Integer use Iteger valueOf    If you wont to convert String to the simple int use Integer parseInt  It works faster     public static Integer valueOf int i            if  i  gt   IntegerCache low  amp  amp  i  lt   IntegerCache high              return IntegerCache cache i    -IntegerCache low            return new Integer i            public static Integer valueOf String s  throws NumberFormatException           return Integer valueOf parseInt s  10           private static class IntegerCache         static final int low   -128        static final int high        static final Integer cache         static              high value may be configured by property         int h   127          String integerCacheHighPropValue               sun misc VM getSavedProperty  java lang Integer IntegerCache high            if  integerCacheHighPropValue    null                try                   int i   parseInt integerCacheHighPropValue                   i   Math max i  127                      Maximum array size is Integer MAX VALUE                 h   Math min i  Integer MAX VALUE -  -low  -1                 catch  NumberFormatException nfe                       If the property cannot be parsed into an int  ignore it                                  high   h           cache   new Integer  high - low    1           int j   low          for int k   0  k  lt  cache length  k                cache k    new Integer j                 range  -128  127  must be interned  JLS7 5 1 7          assert IntegerCache high  gt   127             private IntegerCache            And comparing Integer valueOf 127     Integer valueOf 127  return true  Integer a   127     Compiler converts this line to Integer a   Integer valueOf 127   Integer b   127     Compiler converts this line to Integer b   Integer valueOf 127   a    b     return true    Because it takes the Integer objects with the same references from the cache   But Integer valueOf 128     Integer valueOf 128  is false  because 128 is out of IntegerCache range and it return new Integer  so objects will have different references

User · Answer

Well  the API for Integer valueOf String  does indeed say that the String is interpreted exactly as if it were given to Integer parseInt String   However  valueOf String  returns a new Integer   object whereas parseInt String  returns a primitive int    If you want to enjoy the potential caching benefits of Integer valueOf int   you could also use this eyesore   Integer k   Integer valueOf Integer parseInt  123      Now  if what you want is the object and not the primitive  then using valueOf String  may be more attractive than making a new object out of parseInt String  because the former is consistently present across Integer  Long  Double  etc

User · Answer

From this forum      parseInt   returns primitive integer   type  int   whereby valueOf returns   java lang Integer  which is the object   representative of the integer  There   are circumstances where you might want   an Integer object  instead of   primitive type       Of course  another obvious difference   is that intValue is an instance method   whereby parseInt is a static method

[java] Different between parseInt() and valueOf() in java?

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