Java In A Nutshell, 5th Edition

An IllegalFormatException of this type is thrown by a Formatter when an unknown conversion specifier is included in a format string.

public class UnknownFormatConversionException extends IllegalFormatException { // Public Constructors public UnknownFormatConversionException (String s ); // Public Instance Methods public String getConversion ( ); // Public Methods Overriding Throwable public String getMessage ( ); }