I'm getting an error with System.out.printf()

Question

I am getting a run time error and I cannot figure out why. Although I have figured out that it is happening because of the following line of code.

System.out.printf("\n\nThe total bill for your group is $%.2f before taxes. The HST (13%) will be $%.2f.", totalBill, amountOfTax);

totalBill and amountOfTax are both float type variables.

I am fairly new to programming and have hardly any experience with using printf. I have a very similar line of code earlier in the program that does essentially the same thing and it runs fine.

The error that I am getting is as follows:

Exception in thread "main" java.util.UnknownFormatConversionException: Conversion = ')'
    at java.util.Formatter.checkText(Formatter.java:2579)
    at java.util.Formatter.parse(Formatter.java:2555)
    at java.util.Formatter.format(Formatter.java:2501)
    at java.io.PrintStream.format(PrintStream.java:970)
    at java.io.PrintStream.printf(PrintStream.java:871)
    at RestaurantOrder.main(RestaurantOrder.java:220)

Thanks for any help, I appreciate it!

ps. I should note that I am using Eclipse Luna (4.4.0)

remember that % is an active character for printf. See that "HST (13%)" bit? That's going to be a problem. — Mike 'Pomax' Kamermans
– Mike 'Pomax' Kamermans, Commented Nov 13, 2014 at 0:21

LeffeBrune · Accepted Answer · 2014-11-13 02:33:04Z

7

You need to escape % sign in format string. "13%" becomes "13%%":

System.out.printf("\n\nThe total bill for your group is $%.2f before taxes. " + 
    "The HST (13%%) will be $%.2f.", totalBill, amountOfTax);

edited Nov 13, 2014 at 2:33

answered Nov 13, 2014 at 0:21

LeffeBrune

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Community · Accepted Answer · 2020-06-20 09:12:55Z

2

The percent sign for (13%) is being interpreted as a placeholder. It's looking for characters after the % for details about how to format a variable there, and ) isn't valid.

You meant to have a literal % in the output, not interpreted as a placeholder. It must escaped with another % sign. Try:

System.out.printf(
  "\n\nThe total bill for your group is $%.2f before taxes. The HST (13%%) will be $%.2f.",
  totalBill, amountOfTax);

See the Formatter javadocs for details:

The format specifiers which do not correspond to arguments have the following syntax:
%[flags][width]conversion

And

'%' percent The result is a literal '%' ('\u0025')

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Nov 13, 2014 at 0:21

rgettman

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Jason C · Accepted Answer · 2014-11-13 00:21:20Z

2

You have to escape literal '%' signs in format strings as "%%", e.g. "(13%%)".

printf looks for format specifiers that start with '%', so in your case it sees "%)" and gets confused, wondering what the ')' is for.

Your error message gives a good hint:

Exception in thread "main" java.util.UnknownFormatConversionException: Conversion = ')'

It is choking on a ')', when you see an error like that, look for that character in your string and you will generally find the problem in that vicinity.

The official tutorial isn't really that obvious about it, but a look at the official documentation shows the details.

answered Nov 13, 2014 at 0:21

Jason C

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