$％，。2f代表什么？

Question

I am currently reading the Deitel's book on Java, and came across this code in one of their programs:

public String toString()
{
  return String.format( "%s: %s\n%s: $%,.2f; %s: %.2f", 
     "commission employee", super.toString(), 
     "gross sales", getGrossSales(), 
     "commission rate", getCommissionRate() );
}

As the title says, what does the "$%," in front of the ".2f" represent? I already know what a .2f means.

Answer 1

$是字面上的美元符号，而％是参数％，。2f（带有2位小数和逗号的浮点数）的开头

Answer 2

The $ character means nothing special here. It's just a literal $ to show up in the string. The % character takes it's usual meaning here -- to substitute with a value (here, with 2 decimal places).

Note that it's possible for the $ character to have meaning after the % character. Please see the "Argument Index" section of the Formatter javadocs for details.

Answer 3

%,.2f - 使用逗号格式化带有2个小数位的浮点数。