Java: Literal percent sign in printf statement

The percent sign is escaped using a percent sign:

System.out.printf("%s\t%s\t%1.2f%%\t%1.2f%%\n",ID,pattern,support,confidence);

The complete syntax can be accessed in java docs. This particular information is in the section Conversions of the first link.

The reason the compiler is generating an error is that only a limited amount of characters may follow a backslash. % is not a valid character.

java printf escaping

Escaped percent sign is double percent (%%):

System.out.printf("2 out of 10 is %d%%", 20);

java printf escaping

You can use StringEscapeUtils from Apache Commons Logging utility or escape manually using code for each character.

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