How can I convert a long to int in Java

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Since Java 8 you can use  Math toIntExact long value   See JavaDoc  Math toIntExact     Returns the value of the long argument  throwing an exception if the value overflows an int    Source code of Math toIntExact in JDK 8   public static int toIntExact long value        if   int value    value            throw new ArithmeticException  integer overflow              return  int value

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long x   3120L     take any long value int z    x intValue       you can convert double to int also in the same way  if you needto covert directly then  longvalue intvalue

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You can use the Long wrapper instead of long primitive and call   Long intValue     Java7 intValue   docs  It rounds truncate the long value accordingly to fit in an int

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Shortest  most safe and easiest solution is  long myValue      int asInt   Long valueOf myValue  intValue     Do note  the behavior of Long valueOf is as such  Using this code  System out println  quot Long max   quot    Long MAX VALUE   System out println  quot Int max   quot    Integer MAX VALUE           long maxIntValue   Integer MAX VALUE  System out println  quot Long maxIntValue to int   quot    Long valueOf maxIntValue  intValue     long maxIntValuePlusOne   Integer MAX VALUE   1  System out println  quot Long maxIntValuePlusOne to int   quot    Long valueOf maxIntValuePlusOne  intValue     System out println  quot Long max to int   quot    Long valueOf Long MAX VALUE  intValue      Results into  Long max  9223372036854775807 Int max  2147483647 Long max to int  -1 Long maxIntValue to int  2147483647 Long maxIntValuePlusOne to int  -2147483648

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In Java  a long is a signed 64 bits number  which means you can store numbers between -9 223 372 036 854 775 808 and 9 223 372 036 854 775 807  inclusive    A int  on the other hand  is signed 32 bits number  which means you can store number between -2 147 483 648 and 2 147 483 647  inclusive    So if your long is outside of the values permitted for an int  you will not get a valuable conversion   Details about sizes of primitive Java types here   http   download oracle com javase tutorial java nutsandbolts datatypes html

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I Also Faced This Problem  To Solve This I have first converted my long to String then to int  int i   Integer parseInt String valueOf long

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In Java 8 I do in following way  long l   100L  int i   Math toIntExact l     This method throws ArithmaticException if long value exceed range of int  Thus I am safe from data loss

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If you want to make a safe conversion and enjoy the use of Java8 with Lambda expression You can use it like   val - gt  Optional ofNullable val  map Long  intValue  orElse null

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Long x   100L  int y   x intValue

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Updated  in Java 8    Math toIntExact value     Original Answer    Simple type casting should do it   long l   100000  int i    int  l    Note  however  that large numbers  usually larger than 2147483647 and smaller than -2147483648  will lose some of the bits and would be represented incorrectly   For instance  2147483648 would be represented as -2147483648

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Long l   100  int i   Math round l

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long x   3  int y    int  x    but that assumes that the long can be represented as an int  you do know the difference between the two

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If using Guava library  there are methods Ints checkedCast long  and Ints saturatedCast long  for converting long to int

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Manual typecasting can be done here  long x1   1234567891  int y1    int  x1  System out println  quot in value is  quot    y1

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In Spring  there is a rigorous way to convert a long to int  not only lnog can convert into int any type of class extends Number can convert to other Number type in general here I will show you how to convert a long to int other type vice versa   Long l   1234567L  int i   org springframework util NumberUtils convertNumberToTargetClass l  Integer class

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If direct casting shows error you can do it like this   Long id   100  int int id    int   id   100000

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For small values  casting is enough  long l   42  int i    int  l   However  a long can hold more information than an int  so it s not possible to perfectly convert from long to int  in the general case  If the long holds a number less than or equal to Integer MAX VALUE you can convert it by casting without losing any information  For example  the following sample code  System out println   quot largest long is  quot    Long MAX VALUE    System out println   quot largest int is  quot    Integer MAX VALUE     long x    long Integer MAX VALUE  x    System out println  quot long x  quot    x    int y    int  x  System out println  quot int y  quot    y    produces the following output on my machine  largest long is 9223372036854775807 largest int is 2147483647 long x 2147483648 int y -2147483648  Notice the negative sign on y  Because x held a value one larger than Integer MAX VALUE  int y was unable to hold it   In this case  it wrapped around to the negative numbers  If you wanted to handle this case yourself  you might do something like  if   x  gt   long Integer MAX VALUE            x is too big to convert  throw an exception or something useful   else       y    int x     All of this assumes positive numbers  For negative numbers  use MIN VALUE instead of MAX VALUE

[java] How can I convert a long to int in Java?

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