Java Program to Search a String using RegEx Pattern

Java Programm to Search a String using RegEx Pattern

regex library classes and methods are available in java.util.regex package.

Pattern class is used to create pattern object using regex value which will be used to search sun string.

Matcher class is used to search the sub string based on regex pattern in the string.

This java program is used to find the first matching sub string number format from the string using regular expression pattern.

import java.util.Scanner;
import java.util.regex.*;

public class RegexTest {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		System.out.println("Search regular expression pattern in string"); 
		System.out.println("--------------------------------------------"); 
		System.out.print("Enter String: "); 
		String str = sc.nextLine();
		//Searches Numbers in string
		String pattern ="(\\d+)";
		
		// Creates pattern object
		Pattern regex = Pattern.compile(pattern);
		
		// Creates Matcher object based on string and regex pattern
		Matcher matcher = regex.matcher(str);
		
		System.out.print("Search Result:");
		if(matcher.find()){
			System.out.println(matcher.group());
		} else {
			System.out.println("No Search Results!");
		}
	}
 	
}

D:\Java_Programs>javac RegexTest.java
D:\Java_Programs>java RegexTest 
Search regular expression pattern in string
--------------------------------------------
Enter String: Thsi is testing no 345 of 760
Search Result:345

D:\Java_Programs>javac RegexTest.java
D:\Java_Programs>java RegexTest 
Search regular expression pattern in string
--------------------------------------------
Enter String: This is testing
Search Result:No Search Results!

Java Program to Find Email ID in a String

This java program is used to search email id from the string as user input.

import java.util.Scanner;
import java.util.regex.*;

public class RegexTest {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		System.out.println("Search regular expression pattern in string"); 
		System.out.println("--------------------------------------------"); 
		System.out.print("Enter String: "); 
		String str = sc.nextLine();
		//Searches Email in string
		String pattern ="([a-zA-Z0-9_\\-\\.]+)@([a-zA-Z0-9_\\-\\.]+)\\.([a-zA-Z]{2,5})";
		
		// Creates pattern object
		Pattern regex = Pattern.compile(pattern);
		
		// Creates Matcher object based on string and regex pattern
		Matcher matcher = regex.matcher(str);
		
		System.out.print("Search Result:");
		if(matcher.find()){
			System.out.println(matcher.group());
		} else {
			System.out.println("No Search Results!");
		}	
	}
}

D:\Java_Programs>javac RegexTest.java
D:\Java_Programs>java RegexTest 
Search regular expression pattern in string
--------------------------------------------
Enter String: This is testing to search email abc@gmail.com in codingpointer.com!
Search Result:abc@gmail.com

D:\Java_Programs>javac RegexTest.java
D:\Java_Programs>java RegexTest 
Search regular expression pattern in string
--------------------------------------------
Enter String: This is testing
Search Result:No Search Results!

Java program to Check a String is an Email ID

This java program is used to check the string is an email id or not.

import java.util.Scanner;
import java.util.regex.*;

public class RegexTest {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		System.out.println("Matches regular expression pattern in string"); 
		System.out.println("--------------------------------------------"); 
		System.out.print("Enter String: "); 
		String str = sc.nextLine();
		//Matches email in string
		String pattern ="([a-zA-Z0-9_\\-\\.]+)@([a-zA-Z0-9_\\-\\.]+)\\.([a-zA-Z]{2,5})";
		
		System.out.print("String is an Email ID: ");
		if(str.matches(pattern)){
			System.out.println("True");
		} else {
			System.out.println("False");
		}	
	}
}

D:\Java_Programs>javac RegexTest.java
D:\Java_Programs>java RegexTest 
Matches regular expression pattern in string
--------------------------------------------
Enter String: abc@gmail.com
String is an Email ID: True


D:\Java_Programs>javac RegexTest.java
D:\Java_Programs>java RegexTest 
Matches regular expression pattern in string
--------------------------------------------
Enter String: abc
String is an Email ID: False