Java %,20.2f Explained

Cited from the Book Java How to Program

%,20.2f. The comma (,) formatting flag indicates that the floating-point value should be output with a grouping separator. The actual separator used is specific to the user’s locale (i.e., country). For example, in the United States, the number will be output using commas to separate every three digits and a decimal point to separate the fractional part of the number, as in 1,234.45. The number 20 in the format specification indicates that the value should be output right justified in a field width of 20 characters. The .2 specifies the formatted number’s precision—in this case, the number is rounded to the nearest hundredth and output with two digits to the right of the decimal point.