Consider an interface

public interface NumberFormatter
{
String format(int n);
}

Provide four classes that implement this interface. A DefaultFormatter formats an integer in the usual way. A DecimalSeparatorFormatter formats an integer with decimal separators; for example, one million as 1,000,000. An AccountingFormatter formats negative numbers with parentheses; for example, –1 as (1). A BaseFormatter formats the number in base n, where n is any number between 2 and 36 that is provided in the constructor.