Understanding the $ in Java's format strings

The 2 has nothing to do with the $:

• %     =   Start of format string
• 4$   =   Fourth argument ('d')
• 2     =   width of two (right-aligned)
• s     =   type of String

The 2$ means put the second argument from the list here. The $ follows a number not precedes it. Similarly, 4$ means put the forth argument here.

To clarify, we can break down the %2$2s format into its parts:

• % - indicates this is a format string

• 2$ - shows the second value argument should be put here

• 2 - the format is two characters long

• s - format the value as a String

You can find more information in the documentation.