Trying to multiply double by int in java

Question

I am trying to multiply 1207.87 by 10000 and expecting 12078700.0 but I am getting 1.2078699999999998E7

I understand that its related to precision mistake but how do i rectify this problem

EDIT:-

I simply want to remove the decimal

Answer 1

This is because of float numbers representation .
You can:

• round it Math.round(...)
• or use BigDecimal if you need high precision.

More about What Every Computer Scientist Should Know About Floating-Point Arithmetic .

Answer 2

try this:

1207.87f * 10000

the result will be:

1.20787E7

Answer 3

您需要执行CAST：

(int) 1207.87 * 10000

Answer 4

You cannot rectify this if you use double type. You can if you use BigDecimal .

Answer 5

Try to use decimal format like:

 DecimalFormat f = new DecimalFormat("#0.00");
 f.format(Double.valueOf(yourDouble));

Hope this can help you!

Answer 6

double are stored in exponental precision in java and many other languages. see IEEE754 for more information about float, double and their variant

If you want a integer result, then cast your floating point number, or the result. If you want to just print a floating number in "ordinary notation", then you can use the class NumberFormat

NumberFormat formatter = new DecimalFormat("#0.00");     
System.out.println(formatter.format(4.0));

example taken from here

finally you can use a fixed precision number with the class BigDecimal, but please take care that this is normally not hardware (FPU) accelerated so will slow down a lot your calculation, but will give you fixed error. That kind of number is especially used in simulation where error must be know

Answer 7

You can use formatted output as below:

double ans = 1207.87 * 10000;
System.out.printf("ans: %.0f\n", ans);

Output:

ans: 12078700

Answer 8

Simple way would be this one:

Double j = 1207.87; 
int x = j.intValue(); 
System.out.println(x * 10000);