Regex tag generator in Java

Hi there everyone. 👋 How's your weekend going?
Hope you are doing well. 🙂

So, as you read the title, I am gonna share with you about creating a tag generator using Regex in Java.

Prerequisites 🎒

A bit of knowledge of Java,
A bit of knowledge of Regex,
Willing to code.

Coding ☕️

public class tag {

}

A class will be created when we will start creating a .java file.
I have given its name as tag.java

import java.util.Scanner;
public class tag {

}

Now we will import the java.util.Scanner package.

import java.util.Scanner;
public class tag {

    public static void main(String[] args) {

    }
}

Next, we will add main() inside of which, we will insert our regex equation and input-output method.

import java.util.Scanner;
public class tag {
    private static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) {
        System.out.println("Insert words to get their tags: \n");
        String words = sc.nextLine();

    }
}

In this step, we add the Scanner() to get input and System.out.print() to display a message, as shown in the above code snippet.

import java.util.Scanner;
public class tag {
    private static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) {
        System.out.println("Insert words to get their tags: \n");
        String words = sc.nextLine();
        String regex = "^[0-9a-zA-Z\s][a-zA-Z\s][a-zA-Z0-9\s]+$";

    }
}

Here, we are going to add our **regex** equation.
In this equation:
- First bracket [] is used to get:
  - Any number from 0 to 9,
  - And any character from a to z with any of the upper or lower case.
- Second bracket [] is used to get:
  - Any character from a to z and A to z.
- Third bracket [] is used to get:
  - Any character from a to z and A to Z with numbers from 0 to 9.
- All the three brackets have \s to allow a blank space.
- The caps ^ and dollar sign $ are start and end of the equation.

Final code: ✌🏼

import java.util.Scanner;
public class tag {
    private static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) {
        System.out.println("Insert words to get their tags: \n");
        String words = sc.nextLine();
        String regex = "^[0-9a-zA-Z\s][a-zA-Z\s][a-zA-Z0-9\s]+$";
        if (words.matches(regex)) {
            String tags = words.replaceAll("(?)([ ])", "$1#");
            System.out.println("#" + tags);
        } else {
            System.out.println("Try something else.");
        }
    }
}

At last, we will add two things.
1. if(){}else{} statement to validate and output the required tags.
2. replaceall() as shown in the code to replace blank space with a combination of space plus #, just before every word it will get as input.

Output: 🏆

Screenshot 2020-11-29 at 8.50.51 PM.jpg

Here, when we add multiple words with space between them, it will return them with each word having a hashtag with it.
Thus, we don't need to add the # sign every time while typing a word for multiple hashtags.

So, this is how we can create a tag generator using Regex in Java.
By the way, feel free to share a screenshot if you try this cool project.

Hope you like this article/tutorial of my series Random-Coding.
Please read my other articles of this series as well for more cool and fun projects.

I will meet you through my next article soon. Till then, stay connected with me through Twitter and Discord

Keep Coding, keep growing ☕️

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