Removing the .0 from a double

Question

I am trying to display numbers in a string dynamically, so if the number has decimal's display them but if not don"t show the .0

example: display 5.5 as 5.5 and 5.0 as 5

This is what I have so far: (answer is a double)

double temp = answer;
long temp2 = (long) temp;
if (temp == temp2) {
output = String.valueOf(temp2);
System.out.println(output);

this work's fine up to about 1e18 then will error out because of the maximum size of a Long. So how would I achieve this on bigger numbers like 5.43e86

Answer 1

Use DecimalFormat

double answer = 5.0;
DecimalFormat df = new DecimalFormat("###.#");
System.out.println(df.format(answer));

Answer 2

The DecimalFormat suggestions are the easiest way to handle this. If they aren't sufficient, here's another idea.

If you're starting to hit the maximum values that can be represented by primitives in Java, then you may need to move to BigInteger and BigDecimal.

Try playing around with the BigDecimal.toBigInteger() method coupled with the toString() methods on BigDecimal and BigInteger.