How to check if a double value has no decimal part

Question

I have a double value which I have to display at my UI  Now the condition is that the decimal value of double   0 eg  - 14 0 In that case I have to show only 14 on my UI  Also  the max limit for characters is 5 here   eg - 12 34  the integer value can be no bigger than 2 digits and so is the decimal value for our double   What could be the best way of doing this

User · Answer

either ceil and floor should give the same out out put

Math.ceil(x.y) == Math.floor(x.y)

or simply check for equality with double value

x.y == Math.ceil(x.y)
x.y == Math.floor(x.y)

or

Math.round(x.y) == x.y

User · Answer

You probably want to round the double to 5 decimals or so before comparing since a double can contain very small decimal parts if you have done some calculations with it   double d   10 0  d    3 0     d should be something like 3 3333333333333333333333    d    3 0     d is probably something like 9 9999999999999999999999        d should be 10 0 again but it is not  so you have to use rounding before comparing  d   myRound d  5      d is something like 10 00000 if  fmod d  1 0     0       No decimals else      Decimals   If you are using C   i don t think there is a round-function  so you have to implement it yourself like in  http   www cplusplus com forum general 4011

User · Answer

Interesting little problem  It is a bit tricky  since real numbers  not always represent exact integers  even if they are meant to  so it s important to allow a tolerance    For instance tolerance could be 1E-6  in the unit tests  I kept a rather coarse tolerance to have shorter numbers   None of the answers that I can read now works in this way  so here is my solution   public boolean isInteger double n  double tolerance        double absN   Math abs n       return Math abs absN - Math round absN    lt   tolerance      And the unit test  to make sure it works    Test public void checkIsInteger         final double TOLERANCE   1E-2      assertThat solver isInteger 1  TOLERANCE   is true         assertThat solver isInteger 0 999  TOLERANCE   is true        assertThat solver isInteger 0 9  TOLERANCE   is false         assertThat solver isInteger 1 001  TOLERANCE   is true        assertThat solver isInteger 1 1  TOLERANCE   is false         assertThat solver isInteger -1  TOLERANCE   is true         assertThat solver isInteger -0 999  TOLERANCE   is true        assertThat solver isInteger -0 9  TOLERANCE   is false         assertThat solver isInteger -1 001  TOLERANCE   is true                assertThat solver isInteger -1 1  TOLERANCE   is false

User · Answer

You could simply do d   1    0  to check if double d is a whole

User · Answer

Compare two values  the normal double  and the double after flooring it  If they are the same value  there is no decimal component

User · Answer

All Integers are modulo of 1  So below check must give you the answer   if d   1    0

User · Answer

double d   14 4  if  d- int d   0      System out println  decimal value is there    else     System out println  decimal value is not there

User · Answer

Use number formatter to format the value  as required  Please check this

[java] How to check if a double value has no decimal part

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