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

Figure 16-65. java.util.UnknownFormatConversionException

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