w3resource

Java programming Exercises: Check whether a given string is a valid hex code or not

Java Regular Expression: Exercise-26 with Solution

Write a Java program to check whether a given string is a valid hex code or not.

A hexadecimal color value is a six-digit code preceded by a # sign, and is exactly 6 characters in length. Each character must be an alphabetic character from A-F (uppercase or lowercase.) or a digit from 0-9.

Sample Solution:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String text = "123456";
		System.out.println("Original String: "+text);
		System.out.println("Check the said string is a valid hex code or not? "+validate(text));
		text = "#eaecff";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Check the said string is a valid hex code or not? "+validate(text));
		text = "#FF0000";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Check the said string is a valid hex code or not? "+validate(text));
		text = "#DD5C5C";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Check the said string is a valid hex code or not? "+validate(text));
		text = "#0000000";
		System.out.println("\nOriginal String: "+text);
		System.out.println("Check the said string is a valid hex code or not? "+validate(text));		
	}

   public static boolean validate(String text) {
	   return text.matches("#[0-9A-Fa-f]{6}");
   }
}

Sample Output:

Original String: 123456
Check the said string is a valid hex code or not? false

Original String: #eaecff
Check the said string is a valid hex code or not? true

Original String: #FF0000
Check the said string is a valid hex code or not? true

Original String: #DD5C5C
Check the said string is a valid hex code or not? true

Original String: #0000000
Check the said string is a valid hex code or not? false

Flowchart :

Flowchart: Last n vowels of a given string.

Java Code Editor:

Contribute your code and comments through Disqus.

Previous: Last n vowels of a given string.

Next: Add a dash before and after every vowel in a given string.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Java: Tips of the Day

Split Java String by New Line

String lines[] = string.split("\\r?\\n");

There's only really two newlines (UNIX and Windows) that you need to worry about.

Ref: https://bit.ly/3dHk7ip