How many methods have been defined in the following code?

public class MyClass $\{$

public static void main$($String args$[])\{$

float a $=6$;

printDigit$($a$)$;

$\}$

public static void printDigit$($double a$)\{$

System.out.println$("$This is the number $"+$a$)$;

$\}$

public static void printDigit$($String a$)\{$

System.out.println$("$This is the digit $"+$a$)$;

$\}$

public static void printDigit$($char a$)\{$

System.out.println$("$This is the value $"+$a$)$;

$\}$

$\}$