Please note that String.format(format, args.) is locale-dependent because it formats using the user's default locale, that is, probably with commas and even spaces inside like 123 456,789 or 123,456.789, which may be not exactly what you expect. Double.MIN_VALUE = 4.9E-324 so with 340 digits you are sure not to round your double and lose precision.setMaximumFractionDigits accepts an integer, but its implementation has a maximum digits allowed of DecimalFormat.DOUBLE_FRACTION_DIGITS which equals 340.Why using 340 then for setMaximumFractionDigits? Using the ENGLISH locale makes sure you get a point for decimal separator, wherever your program will run. In the French locale, the decimal separator is a comma, not a point: double myValue = 0.00000021d (df.format(myValue)) // Output: 0īy using DecimalFormat, you are local dependent. (String.format("%.0f", myvalue)) // Output: 0ĭecimalFormat df = new DecimalFormat("0") String.format("%.12f", myvalue) // Output: 0.000000210000īy using setMaximumFractionDigits(0) or %.0f you remove any decimal precision, which is fine for integers/longs but not for double double myValue = 0.00000021d String.format("%s", myvalue) //output: 2.1E-7īy using %f, the default decimal precision is 6, otherwise you can hardcode it, but it results in extra zeros added if you have fewer decimals. (df.format(myValue)) //output: 0.00000021ĭouble.toString() or or FloatingDecimal.toJavaFormatString uses scientific notations if double is less than 10^-3 or greater than or equal to 10^7 double myValue = 0.00000021d If you want to get rid of trailing zeros and locale problems, then you should use: double myValue = 0.00000021d ĭecimalFormat df = new DecimalFormat("0", DecimalFormatSymbols.getInstance(Locale.ENGLISH)) ĭf.setMaximumFractionDigits(340) //340 = DecimalFormat.DOUBLE_FRACTION_DIGITS Please note that String.format(format, args.) is locale-dependent (see answers below).
Please understand the problem before answering. are unacceptable as they both arbitrarily rounds to two decimal places. Sure I can write a function to trim those zeros, but that's lot of performance loss due to string manipulation. I have tried String.format("%f", value), which is close, except I get a lot of trailing zeros for small values. So how do I print these doubles nicely in Java? Given this fact, I choose to use a double type as a single type for all my types, since my largest integer is an unsigned 32-bit number.īut now I have to print these pseudo integers, but the problem is they are also mixed in with actual doubles. A 64-bit double can represent integer +/- 2 53 exactly.
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