Escape % symbol in a java string to apply String.format

Question

In my project (Java/Play framework) I have an error handling routing that checks the response from a web service if the response is an error code, we display the corresponding error message saying what was the problem with the user input, the service checks user input validity.

When the user enter an % symbol, this logic breaks because the error display logic uses

String.format(message, messageArgs);

Which interpolates the messageArgs intro the message String where it finds an %, and if the messageArgs contains an % as well I get an exception.

I need to sanitize, escape or otherwise remove the % from the user inputs, before displaying the message.

message: The requested email address %s is invalid messageArgs: orlybg%@gmail.com

Any advice on how to do this in Java in the simplest, shortest way?

here's a part of the error log

 java.util.UnknownFormatConversionException: Conversion = 'i'
   at java.util.Formatter$FormatSpecifier.conversion(Formatter.java:2646)
   at java.util.Formatter$FormatSpecifier.<init>(Formatter.java:2675)
   at java.util.Formatter.parse(Formatter.java:2528)
   at java.util.Formatter.format(Formatter.java:2469)
   at java.util.Formatter.format(Formatter.java:2423)
   at java.lang.String.format(String.java:2797)
   at controllers.api.PublicAPI.renderAPIError(PublicAPI.java:176)
   at controllers.api.DeviceAPI.setEmailAddress(DeviceAPI.java:736)
   at play.mvc.ActionInvoker.invokeWithContinuation(ActionInvoker.java:557)
   at play.mvc.ActionInvoker.invoke(ActionInvoker.java:508)
   at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:484)
   at play.mvc.ActionInvoker.invokeControllerMethod(ActionInvoker.java:479)
   at play.mvc.ActionInvoker.invoke(ActionInvoker.java:161)
   at Invocation.HTTP Request(Play!)

Thanks!

Can you show the error message? I don't think presence of % in messageArgs will be any issue. — Rohit Jain
– Rohit Jain, Commented Sep 20, 2013 at 18:23

stan · Accepted Answer · 2013-09-21 05:33:50Z

8

In message String, the % sign is escaped with another %. So you will need to double it up: %%
For example: "Bla bla %i bla" -> "Bla bla %%i bla"
In messageArgs String, there is no problem with the % sign and you don't need to escape it

edited Sep 21, 2013 at 5:33

answered Sep 20, 2013 at 18:39

stan

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JaskeyLam · Accepted Answer · 2016-06-15 02:28:28Z

7

Use %% in the formatter string when you need to print string %:

String.format("sendOneSuccessCountRate: %7.2f%%"
              ,sendOneSuccessCountRate //0.95
             );

will give you 95.00%

answered Jun 15, 2016 at 2:28

JaskeyLam

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Archer · Accepted Answer · 2013-09-20 18:34:17Z

1

If you receive java.util.UnknownFormatConversionException: Conversion = 'i' most possibly you use %i in your message trying to format an integer, this is not correct. You must use %d to format the deciamal integer. Full supported conversion specification could be found here.

answered Sep 20, 2013 at 18:34

Archer

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