Question

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How to round a number to n decimal places in Java

I am having difficulties rounding a float to two decimal places. I have tried a few methods I have seen on here including simply just using Math.round(), but no matter what I do I keep getting unusual numbers.

I have a list of floats that I am processing, the first in the list is displayed as 1.2975118E7. What is the E7?

When I use Math.round(f) (f is the float), I get the exact same number.

I know I am doing something wrong, I just am not sure what.

I just want the numbers to be in the format x.xx. The first number should be 1.30, etc.

Answer 1

1.2975118E7 is scientific notation.

1.2975118E7 = 1.2975118 * 10^7 = 12975118

Also, Math.round(f) returns an integer. You can’t use it to get your desired format x.xx.

You could use String.format.

String s = String.format("%.2f", 1.2975118);
// 1.30