How to save decimal in java

Question

Having the following code in Java:

double operation = 890 / 1440;  
System.out.println(operation);  

Result: 0.0

What I want is to save the first 4 decimal digits of this operation (0.6180). Do you know how can I do it?

Answer 1

This is done using BigDecimal

   import java.math.BigDecimal;
import java.math.RoundingMode;


    public class DecimalTest {

        /**
         * @param args
         */
        public static void main(String[] args) {
            double operation = 890.0 / 1440.0;
            BigDecimal big = new BigDecimal(operation);     
            big = big.setScale(4, RoundingMode.HALF_UP);        
            double d2 = big.doubleValue();
            System.out.println(String.format("operation : %s", operation));
            System.out.println(String.format("scaled : %s", d2));
        }
    }

Output

operation : 0.6180555555555556 scaled : 0.6181

Answer 2

Initialize your variable with an expression that evaluates to a double rather than an int:

double operation = 890.0 / 1440.0;

Otherwise the expression is done using integer arithmetic (which ends up truncating the result). That truncated result then gets converted to a double.

Answer 3

You can use the double literal d - otherwise your numbers are considered of type int:

double operation = 890d / 1440d;

Then you can use a NumberFormat to specify the number of digits.

For example:

NumberFormat format = new DecimalFormat("#.####");
System.out.println(format.format(operation));

Answer 4

You can also do something like this:

double result = (double) 890 / 1400;

which prints the following:

0.6180555555555556

You can check how to round up the number here