How do I print a double value without scientific notation using Java?

Question

I want to print a double value in Java without exponential form.

double dexp = 12345678;
System.out.println(\"dexp: \"+dexp);

It shows this

Answer 1

This will work as long as your number is a whole number:

double dnexp = 12345678;
System.out.println("dexp: " + (long)dexp);

If the double variable has precision after the decimal point it will truncate it.

Answer 2

You could use printf() with %f:

double dexp = 12345678;
System.out.printf("dexp: %f\n", dexp);

This will print dexp: 12345678.000000. If you don't want the fractional part, use

System.out.printf("dexp: %.0f\n", dexp);

0 in %.0f means 0 places in fractional part i.e no fractional part. If you want to print fractional part with desired number of decimal places then instead of 0 just provide the number like this %.8f. By default fractional part is printed up to 6 decimal places.

This uses the format specifier language explained in the documentation.

The default toString() format used in your original code is spelled out here.

Answer 3

In short:

If you want to get rid of trailing zeros and Locale problems, then you should use:

double myValue = 0.00000021d;

DecimalFormat df = new DecimalFormat("0", DecimalFormatSymbols.getInstance(Locale.ENGLISH));
df.setMaximumFractionDigits(340); // 340 = DecimalFormat.DOUBLE_FRACTION_DIGITS

System.out.println(df.format(myValue)); // Output: 0.00000021

Explanation:

Why other answers did not suit me:

• Double.toString() or System.out.println or FloatingDecimal.toJavaFormatString uses scientific notations if double is less than 10^-3 or greater than or equal to 10^7

• By 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. Example:

  double myValue = 0.00000021d;
  String.format("%.12f", myvalue); // Output: 0.000000210000
  

• By using setMaximumFractionDigits(0); or %.0f you remove any decimal precision, which is fine for integers/longs, but not for double:

  double myValue = 0.00000021d;
  System.out.println(String.format("%.0f", myvalue)); // Output: 0
  DecimalFormat df = new DecimalFormat("0");
  System.out.println(df.format(myValue)); // Output: 0
  

• By using DecimalFormat, you are local dependent. In French locale, the decimal separator is a comma, not a point:

  double myValue = 0.00000021d;
  DecimalFormat df = new DecimalFormat("0");
  df.setMaximumFractionDigits(340);
  System.out.println(df.format(myvalue)); // Output: 0,00000021
  

  Using the ENGLISH locale makes sure you get a point for decimal separator, wherever your program will run.

Why using 340 then for setMaximumFractionDigits?

Two reasons:

• setMaximumFractionDigits accepts an integer, but its implementation has a maximum digits allowed of DecimalFormat.DOUBLE_FRACTION_DIGITS which equals 340
• Double.MIN_VALUE = 4.9E-324 so with 340 digits you are sure not to round your double and lose precision.

Answer 4

I think everyone had the right idea, but all answers were not straightforward. I can see this being a very useful piece of code. Here is a snippet of what will work:

System.out.println(String.format("%.8f", EnterYourDoubleVariableHere));

the ".8" is where you set the number of decimal places you would like to show.

I am using Eclipse and it worked no problem.

Hope this was helpful. I would appreciate any feedback!

Answer 5

I had this same problem in my production code when I was using it as a string input to a math.Eval() function which takes a string like "x + 20 / 50"

I looked at hundreds of articles... In the end I went with this because of the speed. And because the Eval function was going to convert it back into its own number format eventually and math.Eval() didn't support the trailing E-07 that other methods returned, and anything over 5 dp was too much detail for my application anyway.

This is now used in production code for an application that has 1,000+ users...

double value = 0.0002111d;
String s = Double.toString(((int)(value * 100000.0d))/100000.0d); // Round to 5 dp

s display as:  0.00021

Answer 6

My solution: String str = String.format ("%.0f", yourDouble);