How to modify Double value in android

Question

Suppose, I have a double value.

double dble = 5.91742691

Now can I get that value with two digits after the point. I mean to say,can I get 5.91 from there programmatically?

One more, suppose, I want to get an integer from a double value if the double value is X.9XXXXX. Here I mean to say, I want to compare the AFTER-POINT value. For your understanding here dble's AFTER-POINT value is 91742691. How can I do that?

You can't. Doubles don't have decimal places. They have binary places, and these are incommensurable with decimal places. If you want decimal places you have to use a decimal radix. — user207421, Mar 16 '16 at 03:01

4castle · Accepted Answer · 2016-03-16T02:21:29.903

-1

If you want to truncate a double to 2 decimal places, do

double twoDecDbl = (int)(dble * 100) / 100.0; // 5.91

or

double twoDecDbl = Math.floor(dble * 100) / 100; // 5.91

However, if you want to get the numbers after the decimal place as an integer (which I don't know why you would want to do this), then do

long decimals = Long.parseLong(("" + dble).split("\\.")[1]); // 91742691

Note: The maximum value of an int is 2,147,483,647 (10 digits there), but a double can hold 16 digits after the decimal point, so a long must be used in order to stay safe (can have 19 digits). Alternatively, you can just keep it as a String by removing the wrapping parse.

edited Mar 16 '16 at 02:21

answered Mar 16 '16 at 01:06

4castle

28,713
8
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I've tested all 3 of these. They all work exactly as expected with any value for `dble` (unless of course it is within 2 digits of overflowing a double, which is quite unlikely). – 4castle Mar 16 '16 at 01:24
Ok, how can I get the BEFORE-POINT VALUE? I mean to say, how can I get 5 from 5.91742691? – Muhammad Jobayer Mar 16 '16 at 01:45
UPDATE: I now understand what you meant by AFTER-POINT. It is fixed now. – 4castle Mar 16 '16 at 01:45
@MuhammadJobayer just do `(int)dble` to get the numbers before the point as an integer. After-point was trickier. – 4castle Mar 16 '16 at 01:46
I got. Thanks for help. – Muhammad Jobayer Mar 16 '16 at 01:48
Hey, I fixed my answer for the after-point number. I forgot that the `.` is a special character in regex, so it needs escaping. – 4castle Mar 16 '16 at 01:53
I fixed my answer again so that `int` can't overflow. Read my note. – 4castle Mar 16 '16 at 02:21
Thanks for doing everything – Muhammad Jobayer Mar 16 '16 at 05:23

score -1 · Answer 2 · answered Mar 16 '16 at 01:18

-1

For #1 Try it

NumberFormat formatter = new DecimalFormat("#0.00");
String s = formatter.format(dble);
double num = Double.valueOf(s);

or

dble = Math.floor(dble * 100) / 100;

For #2 Try it

double num = dble - (int)dble;

In case Integer.MIN_VALUE < dble < Integer.MAX_VALUE

answered Mar 16 '16 at 01:18

Pi Vincii

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Your #2 doesn't work. It gives `0.91742691` – 4castle Mar 16 '16 at 01:20
You can convert it to string then remove `0.` at the begining. – Pi Vincii Mar 16 '16 at 01:22
If `number1 = 1.92` and `number2 = 2.1111`, which AFTER-POINT value is greatter? – Pi Vincii Mar 16 '16 at 01:35
It depends, is that value of 1.92 actually 1.92000? Because in that case then 92000 is greater than 1111. Otherwise, 1111 is greater than 92. – 4castle Mar 16 '16 at 01:40
Sorry, your first one worked. But second one was wrong. – Muhammad Jobayer Mar 16 '16 at 01:50

How to modify Double value in android

2 Answers2