Long vs Integer long vs int what to use and when

Question

Sometimes I see API s using long or Long or int or Integer  and I can t figure how the decision is made for that     When should I choose what

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By default use an int  when holding numbers  If the range of int is too small  use a long If the range of long is too small  use BigInteger If you need to handle your numbers as object  for example when putting them into a Collection  handling null       use Integer Long instead

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When it comes to using a very long number that may exceed 32 bits to represent  you may use long to make sure that you ll not have strange behavior    From Java 5 you can use in-boxing and out-boxing features to make the use of int and Integer completely the same  It means that you can do     int myInt   new Integer 11   Integer myInt2   myInt    The in and out boxing allow you to switch between int and Integer without any additional conversion  same for Long Double Short too   You may use int all the time  but Integer contains some helper methods that can help you to do some complex operations with integers  such as Integer parseInt String

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There are a couple of things you can t do with a primitive type    Have a null value synchronize on them Use them as type parameter for a generic class  and related to that  Pass them to an API that works with Objects   Unless you need any of those  you should prefer primitive types  since they require less memory

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An int is a 32-bit integer  a long is a 64-bit integer  Which one to use depends on how large the numbers are that you expect to work with   int and long are primitive types  while Integer and Long are objects  Primitive types are more efficient  but sometimes you need to use objects  for example  Java s collection classes can only work with objects  so if you need a list of integers you have to make it a List lt Integer gt   for example  you can t use int in a List directly

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Integer is a signed 32 bit integer type   Denoted as Int Size    32 bits  4byte  Can hold integers of range -2 147 483 648 to 2 147 483 647 default value is 0     Long is a signed 64 bit integer type   Denoted as Long Size    64 bits  8byte  Can hold integers of range -9 223 372 036 854 775 808 to 9 223 372 036 854 775 807 default value is 0L    If your usage of a variable falls in the 32 bit range  use Int  else use long  Usually long is used for scientific computations and stuff like that need much accuracy   eg  value of pi       An example of choosing one over the other is YouTube s case  They first defined video view counter as an int which was overflowed when more than 2 147 483 647 views where received to a popular video  Since an Int counter cannot store any value more than than its range  YouTube changed the counter to a 64 bit variable and now can count up to 9 223 372 036 854 775 807 views  Understand your data and choose the type which fits as 64 bit variable will take double the memory than a 32 bit variable

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Long is the Object form of long  and Integer is the object form of int   The long uses 64 bits  The int uses 32 bits  and so can only hold numbers up to   2 billion  -231 to  231-1    You should use long and int  except where you need to make use of methods inherited from Object  such as hashcode  Java util collections methods usually use the boxed  Object-wrapped  versions  because they need to work for any Object  and a primitive type  like int or long  is not an Object   Another difference is that long and int are pass-by-value  whereas Long and Integer are pass-by-reference value  like all non-primitive Java types  So if it were possible to modify a Long or Integer  it s not  they re immutable without using JNI code   there would be another reason to use one over the other   A final difference is that a Long or Integer could be null

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a  object Class  Long  versus primitive type  long    At least in Java   b  There are different  even unclear  memory-sizes of the primitive types   Java - all clear  https   docs oracle com javase tutorial java nutsandbolts datatypes html   byte  char    1B    8b short int    2B    16b int             4B    32b long int     8B    64b   C    just mess  https   en wikipedia org wiki C data types   short       16b int          16b     wtf     long       32b long long    64b    mess   -

[java] Long vs Integer, long vs int, what to use and when?

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