Java - Calculator with Decimals

Question

I'm making a calculator using Java. It's all working and I'm now trying to implement decimals. I'm using doubles to store the numbers. I have a solution the following solution:

decPoints++; //decPoints holds the current number of numbers after the decimal point
currentVal = currentVal + (n/Math.pow(10, decPoints)); //n is the number that is to be added on

This works, however it results in rounding errors e.g. 3.369 would become 3.689999..

Is there an easy solution to this problem or another way to implement decimals?

Thanks in advance!

Do you mean 3.369 comes out as 3.368999999...? – Mr. Adobo Mar 06 '13 at 15:55 — Mr. Adobo, Mar 06 '13 at 15:55
Yes sorry, bad wording there. – DJDMorrison Mar 06 '13 at 15:56 — DJDMorrison, Mar 06 '13 at 15:56

score -1 · Answer 1 · answered Mar 06 '13 at 15:55

-1

Never mind, found a solution myself using BigDecimals.

decPoints++;
currentVal = currentVal + (n/Math.pow(10, decPoints));

BigDecimal bd = new BigDecimal(currentVal);
bd = bd.setScale(decPoints, BigDecimal.ROUND_HALF_UP);
currentVal = bd.doubleValue();

answered Mar 06 '13 at 15:55

DJDMorrison

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That only works for a few carefully chosen values. You should work in `BigDecimals` throughout. – user207421 Mar 06 '13 at 21:58

Java - Calculator with Decimals

1 Answers1