🔗 Basic String Handling

Complete a function, solution, that checks whether the string s has a length of 4 or 6 and consists only of digits. For example, if s is "a234" it returns False, and if it is "1234" it returns True.

• s is a string of length 1 to 8, inclusive.

Only strings that satisfy all of the following conditions should return true; everything else should return false.

• All characters consist of digits
• The length is 4 characters or 6 characters (not 4 to 6)

This can be solved cleanly using a regular expression. Build a regex, and if the string matches it, return true; otherwise, return false.

• Regex: ^([0-9]{4}|[0-9]{6})$
• [0-9] — a digit
• {4} — 4 characters
• | — OR
• ^ — start of string
• $ — end of string

This is a regex that matches strings that are entirely a 4-digit or 6-digit number.

JAVA
import java.util.regex.Pattern;

/**
 * Basic String Handling class
 *
 * @author RWB
 * @since 2021.12.13 Mon 15:38:26
 */
class Solution
{
	/**
	 * Method that returns the answer
	 *
	 * @param s: [String] string
	 *
	 * @return [boolean] the answer
	 */
	public boolean solution(String s)
	{
		return Pattern.matches("^([0-9]{4}|[0-9]{6})$", s);
	}
}