Read All the Emails Present in a File in Java

As per the problem statement we need to find all the Emails present in the file.

Let’s explore the article to see how it can be done by using Java programming language.

To Show You Some Instances

Instance-1

Suppose there is given paragraph and it contains many different email ids and we want to extract all the mail id present in that paragraph. For e.g. −

“I am a boy with email boy54@gmail.com. My friend’s email is friend78@gmail.com.”.”

From the above paragraph, we need to take out the given two mail id in the paragraph i.e., boy54@gmail.com and friend78@gmail.com. 

Instance-2

Suppose there is given paragraph and it contains many different email ids and we want to extract all the mail id present in that paragraph. For e.g.

“Hey, I am Rakesh Agarwal, my mail id is rakesh@tutorialspoint.com. My friend’s email is prakash@gmail.com.”

From the above paragraph we need to take out the given two mail id in the paragraph i.e., rakesh@tutorialspoint.com and prakash@gmail.com.

Instance-3

Suppose there is given paragraph and it contains many different email ids and we want to extract all the mail id present in that paragraph. For e.g.

“Hey, I am Rakesh Agarwal, my mail id is rakesh@yahoo.com.

From the above paragraph we need to take out the given mail id in the paragraph i.e., rakesh@yahoo.com. 

Algorithm

• Step 1 − Import the necessary java libraries.

• Step 2 − Define the regular expression for the matching pattern.

• Step 3 − Assign the location of the text file or take input from the user.

• Step 4 − Matching the required format using matcher method.

Syntax

Compile() - The compile() method is used to match text or expression against a regular expression more than one time. The compile() method is used to compile the given regular expression passed as the string. It belongs to the Pattern class.

matcher() - The matcher() method performs match operations on a character sequence by interpreting a Pattern.
readLine() - The readLine() method is used to read a given line from text. It takes input from the console screen and it belongs to the BufferReader class.

Multiple Approaches

We have provided the solution in different approaches.

• By Using Input from File

• By Using User Input from Console

Let’s see the program along with its output one by one.

Approach-1: By Using Input from File

Example

In this method we will take input from the system itself as a text file and filter out all the email id present in that text file.

import java.util.regex.*; 
import java.io.*; 
public class Main { 
   public static void main(String[] args) throws IOException { 
   
      // Regular expression for email id and assigning it to pattern method
      Pattern pat=Pattern.compile( "[a-zA-Z0-9]" + "[a-zA-Z0-9_.]" + "*@[a-zA-Z0-9]" + "+([.][a-zA-Z]+)+");
      
      //Assigning the location of the text file
      BufferedReader b = new BufferedReader(new FileReader("E:\file1.txt"));
      
      //reading yo.txt file 
      String l = b.readLine(); 
      while (l != null) { 
      
         //Matching the required format using matcher method
         Matcher mat = pat.matcher(l); 
         while (mat.find()) { 
            System.out.println(mat.group()); 
         } 
         l = b.readLine(); 
      }  
   } 
}

Output

abhaprakash@123.com
abhaprakash@tutorialspoint.com
rancho45@gmail.com
y@gmail.com
asifa.sandal120098@yahoo.com
welcometoCodespeedy@hotmail.com.abcxyz
12345@qwerty.asd

Approach-2: By Using Input from Console

Example

In this method we will take input from the user and filter out all the email id present in it.

import java.util.regex.*; 
import java.io.*; 
import java.util.*;
public class Main { 
   public static void main(String[] args) throws IOException { 
   
      // Regular expression for email id and assigning it to pattern method
      Pattern pat=Pattern.compile( "[a-zA-Z0-9]" + "[a-zA-Z0-9_.]" + "*@[a-zA-Z0-9]" + "+([.][a-zA-Z]+)+");
      
      //Taking input from the console
      Scanner b = new Scanner(System.in);
      System.out.println("Write the Paragraph containing email ids");
      
      //reading yo.txt file 
      String l = b.nextLine(); 
      System.out.println("\nEmail ids are-"); 
      while (l != null) {
      
         //Matching the required format using matcher method
         Matcher mat = pat.matcher(l); 
         while (mat.find()) { 
            System.out.println(mat.group());
         } 
         l = b.nextLine();
      }  
   } 
}

Output

Write the Paragraph containing email ids
abhaprakash@123.com
abhaprakash@com
abhaprakash$gmail.com
abha
abhaprakash@tutorialspoint.com
rancho45@gmail.com
y@gmail.com
asifa.sandal120098@yahoo.com
welcometoCodespeedy@hotmail.com.abcxyz
12345@qwerty.asd

Email ids are-
abhaprakash@123.com
abhaprakash@tutorialspoint.com
rancho45@gmail.com
y@gmail.com
asifa.sandal120098@yahoo.com
welcometoCodespeedy@hotmail.com.abcxyz
12345@qwerty.asd

In this article, we explored how to read all the emails present in the file in Java.