how to change the double value as four decimal point value

Question

Possible Duplicate:
Round a double to 2 significant figures after decimal point

i've got lat and long point like this,

x1: 11.955165229802363
y1: 79.8232913017273

i need to convert 4 decimal point

x1 = 11.9552
y1 = 79.8233

Is this for display purposes or do you want to truncate the value of the digit? — Sam, Aug 03 '12 at 11:56

score 8 · Accepted Answer · answered Aug 03 '12 at 11:55

8

Try

double roundTwoDecimals(double d)
{
    DecimalFormat twoDForm = new DecimalFormat("#.####");
    return Double.valueOf(twoDForm.format(d));
}

answered Aug 03 '12 at 11:55

Chirag

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What is the round mode with this? – Paul Vargas Aug 03 '12 at 12:04
instead of two mathematical operations you create two new objects and call 3 methods only to show 4 digits after dot, so much overhead – marwinXXII Aug 03 '12 at 19:23

score 2 · Answer 2 · answered Aug 03 '12 at 11:59

2

Math.ceil(x1* 10000) / 10000

Replace 10000 with 10^N, where N is number of digits after dot. In case of 4 digits after dot, precision shouldn't be lost.

answered Aug 03 '12 at 11:59

marwinXXII

1,456
14
21

score 1 · Answer 3 · answered Aug 03 '12 at 11:57

1

Try this

String.format("%.4f", 11.955165229802363)

answered Aug 03 '12 at 11:57

Pramod Kumar

7,914
5
28
37

score 1 · Answer 4 · answered Aug 03 '12 at 11:59

1

Assuming you want to round/truncate the decimal, and speed is not a large consideration, you want to use BigDecimal(BigInteger unscaledVal, int scale) with scale set to 4.

answered Aug 03 '12 at 11:59

Sam

2,939
19
17

score 0 · Answer 5 · answered Aug 03 '12 at 11:55

0

DecimalFormat dtime = new DecimalFormat("#.####"); 
                                           ^^^^
x1= Double.valueOf(dtime.format(x1));

answered Aug 03 '12 at 11:55

MAC

15,799
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2

I think you may have forgotten a line here; dtime isn't used. – Jim Kiley Aug 03 '12 at 11:58

score 0 · Answer 6 · answered Aug 03 '12 at 11:59

0

float round = Round(num,4);
System.out.println("Rounded data: " + round);
}

public float Round(float Rval, int Rpl) {
float p = (float)Math.pow(10,Rpl);
Rval = Rval * p;
float tmp = Math.round(Rval);
return (float)tmp/p;
}

answered Aug 03 '12 at 11:59

User404

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score 0 · Answer 7 · answered Aug 03 '12 at 12:01

If you only want to display the value like that, use a DecimalFormat to convert the value to a string, then display that.

If you really want to round it to four digits, you can achieve that by multiplying by 10000, rounding, then dividing again. However, I would advise against it, since not all decimal numbers can be properly represented in floating point format. Changes are you'll just get something like you already had.

If you really want four digits to work with as an internal state, use a BigDecimal instead. It is properly equipped to do what you want.

how to change the double value as four decimal point value

7 Answers7