Checking if a number is an Integer in Java

Question

Is there any method or quick way to check whether a number is an Integer  belongs to Z field  in Java   I thought of maybe subtracting it from the rounded number  but I didn t find any method that will help me with this   Where should I check  Integer Api

User · Answer

change x to 1 and output is integer  else its not an integer add to count example whole numbers  decimal numbers etc            double x   1 1     int count   0     if  x     int x               System out println  X is an integer      x          count            System out println  This has been added to the count     count        else             System out println  X is not an integer      x          System out println  This has not been added to the count     count

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if  number 1   0                System out println  not a integer              else               System out println  integer

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With Z I assume you mean Integers   i e 3 -5 77 not 3 14  4 02 etc   A regular expression may help   Pattern isInteger   Pattern compile    d

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in C language   but the algo is same   include  lt stdio h gt   int main      float x   77 6     if x- int  x gt 0      printf  True  it is float       else     printf  False  not float                return 0

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Check if the passed argument is an integer value         param number double     return true if the passed argument is an integer value      boolean isInteger double number        return number   1    0    if the modulus remainder of the division  of the argument number  with 1 is 0 then return true otherwise false

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int x   3    if ceil x     x       System out println  x is an integer        else      System out println  x is not an integer

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One example more     double a   1 00  if floor a     a          a is an integer   else        a is not an integer      In this example  ceil can be used and have the exact same effect

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double x    2 15       if Math floor x     x           System out println  an integer          else          System out println  not an integer            I think you can similarly use the Math ceil   method to verify whether x is an integer or not  This works because Math ceil or Math floor rounds up x to the nearest integer  say y  and if x  y then our original  x  was an integer

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if you re talking floating point values  you have to be very careful due to the nature of the format    the best way that i know of doing this is deciding on some epsilon value  say  0 000001f  and then doing something like this   boolean nearZero float f        return   -episilon  lt  f   amp  amp   f  lt epsilon         then  if nearZero z- int z            do stuff     essentially you re checking to see if z and the integer case of z have the same magnitude within some tolerance  This is necessary because floating are inherently imprecise   NOTE  HOWEVER  this will probably break if your floats have magnitude greater than Integer MAX VALUE  2147483647   and you should be aware that it is by necessity impossible to check for integral-ness on floats above that value

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Quick and dirty     if  x     int x               edit  This is assuming x is already in some other numeric form   If you re dealing with strings  look into Integer parseInt

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Check if ceil function and floor function returns the same value  static boolean isInteger int n      return  int  Math ceil n       int  Math floor n

[java] Checking if a number is an Integer in Java

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