Aadhaar Number Validator Using Java

1. The program starts by defining a file path to the text file that will be read.
2. Inside the main method, a Scanner object is created to read the file.
3. A while loop is used to iterate through each word in the file using the Scanner object.
4. The regular expression pattern \\d{4}-\\d{4}-\\d{4} is defined to match Aadhaar numbers in the format of "####-####-####" (four digits, a hyphen, four digits, a hyphen, and four digits).
5. Each word from the file is checked for the presence of a colon (":") using the lastIndexOf method. If a colon is found, the program assumes that the Aadhaar number is present after the colon.
6. The Aadhaar number is extracted from the word using substring starting from the index after the colon.
7. A Pattern object is created using the regular expression pattern.
8. The Matcher object is initialized with the extracted number and the pattern.
9. The find method of the Matcher object is called to check if the number matches the defined pattern.
10. If a match is found, it prints that the number is a valid Aadhaar number. Otherwise, it prints that the number is not a valid Aadhaar number.
11. The catch block handles the FileNotFoundException in case the specified file is not found.

Note: The code uses @SuppressWarnings("resource") annotation, which suggests that the Scanner object is not closed explicitly because it goes out of scope when the loop ends. However, it's generally recommended to close resources like Scanner explicitly using the close method or by utilizing the try-with-resources statement to ensure proper resource management.

Make sure to provide a valid file path to an existing text file for the program to read and search for Aadhaar numbers.

TextFile Content :

user1:2222-3333-4444
user2:4444-5555-32

Result: