将十进制（分数）值的双精度值转换为java

Question

I have below code:

Double a = new Double((123456798/1000000)); //123456798 this value comes from client side as a `int`
DecimalFormat df = new DecimalFormat("###.###");            
log.info("a :"+a+" df "+df.format(a.doubleValue()));

output:

a :123.0 df 123
//i want output like this, a :123.xxx fd 123.xxx

please help

UPDATE:

123456798 this value comes from client side as a int so i cant do it as 123456798.0 (or something)

Answer 1

123456798 and 1000000 are int literals, so dividing them will use integer arithmetic, and yield 123 . Instead, you could use floating point literals in order to use floating point arithmetic:

Double a = new Double((123456798.0/1000000.0));
DecimalFormat df = new DecimalFormat("###.###");            
log.info("a :"+a+" df "+df.format(a.doubleValue()));

Answer 2

Any one value in the division should be float or double.

Double a = new Double((123456798.0/1000000));

or

Double a = new Double((123456798/1000000.0));

if you are getting these values in variables, then multiply it with 1.0

like

Double a = new Double((variable*1.0/1000000));

Answer 3

Put it like that

Double a = new Double((123456798.0/1000000.0)); // <- note ".0"

the reason of the misbehavior is the integer division :

  123456798/1000000 

is the integer value, while

  123456798.0/1000000.0

is the floating point one (double)

Answer 4

Double a = new Double((123456798/1000000));

You are doing integer division here. Make one of the constants a double , so that floating-point division is done. Also, why are you using Double ? It's better to use the primitive type double .

double a = 123456798.0 / 1000000;

Or simply, since they are constants:

double a = 123.456789;

Answer 5

您执行整数除法，这就是a不正确的原因：

Double a = new Double(123456798.0/1000000);