Java Double/Integer

问题

int a = 1;
int b = 10;
int c = 3;

int d = (1/10)*3

System.out.println(d)

Result: 0

How do i make this Calculation work ? and round up or down ? It should be: (1/10)*3 = 0.1 * 3 = 0.3 = 0 and (4/10)*3 = 0.4 * 3 = 1.2 = 1

Thanks a lot!

回答1:

1 / 10

This is integer division and as integer division the result is 0. Then 0 * 3 = 0

You can use double literals:

1.0 / 10.0

回答2:

Try:

int d = (int) (((double)4/10)*3);

回答3:

1/10

This line return 0.so 0*3=0.Use double instead of int

回答4:

as both a and b are integer so the output will also be int which makes 1/10 as 0 and then 0*3=0

回答5:

You will want to perform the calculation using floating-point representation. Then you can cast the result back to an integer.

回答6:

I note that you refer in your question to rounding up/down.

Math.round() will help you here.

Returns the closest long to the argument. The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type long.

回答7:

This will works

int a = 1;
int b = 10;
int c = 3;    
int d = (1*3/10);    
System.out.println(d);

来源：https://stackoverflow.com/questions/12105494/java-double-integer