Javafaker API – numerify(), letterify() and bothify() methods of Faker Class

Method names in the title might confuse you but those are the best words to give them when you go through this post.

If you want to create a string in a fixed format like “Amod123Mahajan” or “[email protected]” etc then the above methods will be useful for you.

I have used below Javafaker API dependency:-

  com.github.javafaker javafaker 1.0.2

I have covered Javafaker API below posts. You can go through it to understand more about Javafaker API.

Javafaker API – Generate Real-Time Fake Data – Faker Class

Generate Random Numbers Using Javafaker API – Java

String numerify(String numberString)

As per official Javadoc, the above method returns a string with the ‘#‘ characters in the parameter replaced with random digits between 0-9 inclusive.

For example, the string “ABC##EFG” could be replaced with a string like “ABC99EFG“.

In simple words, if you want to have a number/s at specific places of a string just put a hash(“#”) there and numerify() method will put a random number there.

package FakerClassExamples;

import com.github.javafaker.Faker;

public class NumerifyExample {
        public static void main(String[] args) {

                Faker faker = new Faker();
                System.out.println(faker.numerify("Amod##Mahajan"));
                System.out.println(faker.numerify("A#mod##Maha#jan"));
                System.out.println(faker.numerify("A#mod##Mahajan453"));      
        }
}

Amod45Mahajan
A4mod23Maha2jan
A6mod39Mahajan453

String letterify(String letterString)

As per official Javadoc, the above method returns a string with the ‘?’ characters in the parameter replaced with random alphabetic characters.

For example, the string “12??34” could be replaced with a string like “12ab34”.

In simple words, if you want to have an alphabet/s at specific places of a string just put a hash(“?”) there and letterify() method will put a random alphabet there.

By default, it will put lower case letters. If you want it should put upper case letters then you can use below-overloaded method.

public java.lang.String letterify(java.lang.String letterString, boolean isUpper)

package FakerClassExamples;

import com.github.javafaker.Faker;

public class LetterifyExample {
        public static void main(String[] args) {

                Faker faker = new Faker();
                System.out.println(faker.letterify("167??789"));
                System.out.println(faker.letterify("?34?45??"));
                System.out.println(faker.letterify("Amod??Maha?an")); 
        }
}

167cn789
s34r45tv
AmodvnMahaban

String bothify(String string)

Applies both a numerify(String) and a letterify(String) over the incoming string.

package FakerClassExamples;

import com.github.javafaker.Faker;

public class BothifyExample {
        public static void main(String[] args) {

                Faker faker = new Faker();
                System.out.println(faker.bothify("Amod##167??789"));
                System.out.println(faker.bothify("?34?45??"));
                System.out.println(faker.bothify("Amod##Maha?an"));   
        }
}

Amod18167mi789
c34t45bh
Amod59Mahacan

These methods will be helpful to create random email ids or alphanumeric strings etc.

You can clone above Git Repo from here.

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